QUICKIE DEMONSTRATIONSOFSCIENTIFIC PRINCIPLES1. Spontaneous ignition can be affected with

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QUICKIE DEMONSTRATIONSOFSCIENTIFIC PRINCIPLES1. Spontaneous ignition can be affected with a half teaspoon of sodiumperoxide placed on a two-inch cone of starch, sawdust, or finelychopped paper. Lay a small chip of ice on the cone. Sufficient heatand oxygen will be released by the reaction of water from the ice withthe sodium peroxide to ignite the material. Kindling temperature andoxidation can be discussed following the demonstration.2. Structure of a Bunsen flame can be demonstrated by adjusting theflame to above five centimeters and holding a splint horizontally atvarious levels. Heat intensity for each level will be indicated bythe degree of scorch on the splint. This may be varied by using aplain card held perpendicular and slightly tilted in the flame. Ascorch pattern will appear showing heat intensities of various areasof the flame. A wire gauze held in the flame will show by its glowthe same conditions. Probe the flame with a small thermocoupleconnected to a sensitive ammeter and interpret.3. Allow students to check the pH of their own saliva by using Hydrionpaper. The color chart (usually on the Hydrion vial) will indicatequite a range of pH through the class.4. Pass cut strips of cobalt chloride paper directly from thedesiccator to some or all of the students. Have them hold papertightly in the palm of their hand for a minute. They will note achange of color. Various explanations will ensue.5. Molecules of water have spaces between them as evidenced when along test tube or graduate is filled three-fourths full of water andthen completely filled carefully to capacity with alcohol. Placethumb over end of container and invert to mix the liquids. Thecontainer will no longer be fulled to capacity.6. Using a small container rather than a large one in a gas generatorgives a quicker yield of undiluted gas. Carbon dioxide can be madequickly by heating sodium bicarbonate in a test tube generator.7. Dramatization of valence in simple reactions can be shown by twogirls holding the other's hands (representing oxygen molecules) andfour boys, each with one hand in his pocket but holding another boy'shand (representing hydrogen molecules.) The three moleculesrepresented will break apart at the introduction of a suitablecatalyst (represented by a popular dance tune) to form H-O-H.8. One demonstration seldom offers so many illustrations as does"Barking Dogs," yet remains so simple to perform. Dissolve a smallamount of white phosphorus in carbon disulfide. CAREFUL! FLAMMABLE!A few drops of this solution on filter papers placed on top of anumber of empty glass cylinders of varying capacities will illustrate: a- Solubility and physical change as P dissolves in CS2 b- Evaporation as CS2 evaporates leaving P on filter paper c- Settling of diffusion of a heavy gas as CS2 mixes with air incylinders d- Spontaneous ignition as P catches fire on papers e- Oxidation and combustion a P catches fire and paper burns f- Combustion and explosion as CS2 and air explode in cylinder g- Incomplete combustion as evident by sulfur deposited oncylinder walls h- Natural frequency of cylinders differ as pitch of explosiondiffer9. Is so-called suction a push or a pull? Arrange a flask fitted witha two hole stopper and a glass tube extending well down into the flaskwhich is completely filled with water. A good-natured student isasked to "suck" water through the glass tube while the instructorholds his finger over the other hole of the stopper. On student'sfailure to get any water out of the flask, instructor might remark,"Jim is not as big a sucker as we thought." After appropriatecomments and removing his finger from the hole, the instructor asksthe boy to try again. Suddenly the sucker succeeds. This is followedby explanation, after laughter subsides, showing how the experimentanswers the problem.10. Mix a little concentrated sulfuric acid (CARE!) and potassiumpermanganate in an evaporating dish. Dip a glass rod into the mixtureand immediately touch the rod with attached mixture to the wick of analcohol lamp. The alcohol ignites.11. Relative vapor pressures of liquids can readily be shown. Attachmanometer tubes to three bell jars of same size/ Fill tubes withcolored light liquids. Place the bell jars over dishes containingwater, alcohol, and ether all at the same temperature. Dishes andbell jars may need to be set on glass plates in order that air tightseals can be obtained.12. To demonstrate how water aids chemical reaction, add about a gramof potassium bitartrate with an equal amount of sodium bicarbonate toa test tube. Shake and note no reaction. (Explain that these are theessentials of cream of tartar baking powder which may keep for monthson the grocer's shelf) Add a little water and the effect is evident.Ions are more active than atoms or molecules and water probably actsas a catalyst or at least promotes ionization.13. Encourage students to think, speak, and write more precisely.Illustrate by using a meaningless advertising slogan: "TheRolls-mobile is bigger and better: -than- (a) a diddie car (b) afreight car (c) last year's model.14. Oxygen may be prepared by the action of enzymes in yeast on six(or three) percent solution of hydrogen peroxide, surface action ofmanganese dioxide on hydrogen peroxide, heating sodium nitrate, or theinteraction of sodium peroxide on water.15. Show samples of chemicals mentioned in test as they are discussed.The difference in chemical and physical properties of substances ismade real to the students by such simple means as, for example,heating separate test tubes of iodine and sulfur.16. When studying minerals show a simple separation process where coalis separated from shale through flotation. A zinc chloride solutioncan be made in which coal will float and shale sink.17. Transparent boxes used as containers for samples to be passedaround in class can be dressed up with labels to make the specimensattractive.18. The distinction between mixing and combining can be shown byputting a mixture of of two parts hydrogen or natural gas with onepart of oxygen into a syrup can equipped with a spark plug. A highfrequency coil can be used to furnish the spark which will causecombustion and combine the gases.19. Match sticks are chemically treated except the tip where they areheld by machines during the process of manufacture. Burn a matchcompletely and show the difference between the ash or char left of thetreated and untreated region.20. Produce samples of substances made in your own laboratory such ascold cream, hair tonic, insecticides, ink, etc. Mercuric thiocyanatemade into a small cone by the aid of dextrin forms a pharaohs serpentwhen burned. Such items always create interest. ... the mercurycompound would be rather poisonous; avoid breathing vapor.21. Cup hands over an unlighted Bunsen burner to collect gas. Ignitethis gas at a lighted burner and carry the flame back to ignite thegas of the first burner to show that flame results from a burning gas.... one of our people tried this without burning himself; it didn'twork as described tho.22. Hold a match head in a Bunsen flame in such a way that the stickburns but the head does not ignite. This is evidence that some partsof the flame are cool.23. Mix (don't grind) one part sugar with three parts potassiumchlorate. Incorporate Na, Ba, Ca, Sr, Cu, and BO3 ions with portionsof the mixture on a long trough. Light one end and observe thedifferent colors which appear in the flame.24. The amphoteric nature of aluminum can be demonstrated by reactingaluminum sulfate with sodium hydroxide to obtain aluminum hydroxideprecipitate. Treat the aluminum hydroxide precipitate with moresodium hydroxide and get sodium aluminate and water. These lastproducts treated with hydrochloric acid precipitate aluminumhydroxide. This precipitate treated with more hydrochloric acidyields aluminum chloride and water.25. The green flame characteristics of borax can be shown by burningalcohol to which a little sulfuric acid and borax have been added.26. Crystallization of a supersaturated solution can be shown easilyby adding sodium thiosulfate to hot water and letting it cool slowly.Scratching the test tube causes the contents to become practically asolid in a short time. Melt sodium acetate in its own water ofcrystallization by using a double boiler. The resultingsupersaturated solution behaves in a spectacular manner. ... We'venever got scratching to work. Seeding the solution with a crystal isbest.27. After teaching the method of determining the formulas of acompound from its percentage composition, give the students thecompound containing boron 3.6%, uranium 78.9%, nitrogen 4.6%, andpotassium 12.9% See who gets the right answer, BUNK, first.28. Flash cards are useful in learning symbols for elements as well asthe names of ions.29. Games can also be played using cards with symbols and names onthem, using the rules of Old Maid or such games. To match up cards,one must have the symbols and the other have the name of the ion orelement.30. Compounds of elements having high an low valences may be named bythe association - (hi-ic);(lo-ous).31. Oxidation reduction relation to gain and loss of electrons can beimpressed by use of the mnemonic "LEO is Leo the lion, GER, is hisroar," The equation 2HgCl2 + SnCl2 --> Hg2Cl2 + SnCl4 ,tin has LostElectrons and is Oxidized. Mercury has Gained Electrons and isReduced. A healthy roar will fix the electron action permanently inthe student's mind.32. Show emf produced between solutions of different concentrations byusing two copper discs attached to insulated wire and suspended in adilute copper sulfate solution, then drop a few crystals of coppersulfate in to make the bottom layer more concentrated. Connect theelectrodes to a sensitive malliameter or galvameter.33. Gases are held in compressed volume by molecular forces ofocculsion. Fill a large mouth bottle with granular activatedcharcoal. Fit the bottle with a two-hole stopper carrying a thistletube and delivery tube. Announce that this filled bottle containsmore than its volume. Proceed to demonstrate by slowly filling thebottle with water while collecting the gases over water from thedelivery tube.34. Using a fine nozzle blow pipe prepared from a glass tube, blowsmall bubbles in a pan of water containing "Tide" or "Joy". Thebubbles will arrange themselves in pattern somewhat like molecules asthey form crystals.35. Form a paste in a small beaker of para-nitroanaline withconcentrated sulfuric acid. Heat this mixture over a Bunsen flame.The reaction produces a long sausage-like plastic mass which is quitespectacular.36. The gas laws may be illustrated by a device prepared by drillingholes near each end and in the center of a small board about the sizeof a yardstick. Label each hole appropriately; Pressure, Temperature,and Volume. Show by pivoting at center hole (Temperature) iftemperature remains constant and pressure rises, the volume will lower(decrease) etc. Other variations will show different aspects of thelaws.37. Fill with natural gas a half gallon syrup can having a hole cut onthe side near the bottom and another in center of lid. Ignite the gasas it comes from the hole in the lid. Flame will at first be largeand luminous, gradually changing to intensely hot flame as air isdrawn in from the bottom hole and mixed with the gas. The gas and airmixture will eventually explode on reaching the proper proportions inmixture.38. Using a side-arm flask with a small hole in the bottom and aone-hole stopper fitted with a ten-inch piece of glass tubing, one isable to demonstrate air burning in an atmosphere of gas inside theflask. At the same time another flame burning in an atmosphere of aircan be lighted at the hole in the bottom of the flask. To set up theapparatus, invert the flask and insert the stopper and glass tube sothat the tube extends into the bulge of flask some distance above theside-arm opening. Introduce the fuel gas through the side-arm,keeping the hole in the bottom of the flask closed until the gasissues through the glass tube. Ignite the gas coming from the glasstube, then open the hole in top of apparatus. The flame will travelup the glass tube and continue to burn inside the flask? The unburnedgases issuing at the top hole may now be ignited. A mysterious effectof burning only air is produced if one can arrange to cancel the gasintake.39. The effect of the sun setting through dust-laden atmosphere can bedemonstrated by throwing a spot light through a 700 mL water solutionof five grams of sodium thiosulfate to which 5 mL of concentratedhydrochloric acid has just been added. As the colloidal sulfur forms,scattered blue light can be seen at a ninety degree angle from thebeam. On the screen or wall the spot from the beam changes from whitethrough yellow, red, and finally is blacked out completely.40. Light gases diffuse downward. Fill a wide mouth bottle withhydrogen. Invert over a like bottle filled with air. While waitingfor the diffusion to take place, be democratic and allow the class tovote for what they think is most likely to happen. These possibilitiesmay exist: (a) the hydrogen being lighter will remain in the topbottle, (b) the gases will mix together, (c) all the hydrogen will goto the bottom bottle, (e) non-voters do not know what will happen. ATthe end of about five minutes, test each bottle with a burning splint.Apply that many people vote with too little facts and information.41. Build a miniature volcanic cone with deep depression in top.Place in the depression some ammonium dichromate mixed with a smallamount of powdered magnesium. Push a piece of magnesium ribbon intothe mixture. Light the ribbon to ignite the mixture. A realisticvolcanic action ensues. (protect desk top from possible particlescatter) ...a beautiful demonstration-- write the equation on theboard to help explain action. Cutting the end of the Mg ribbon intoshreds aids igniting42. Five milliliters of calcium acetate poured into forty-fivemilliliters of ethyl alcohol will form a false gel that resemblescanned heat.43. Iodine crystals added to ammonium hydroxide form nitrogentriiodide. These crystals are extremely sensitive when dry and willexplode on being touched delicately with a feather.44. A Halo type shampoo poured on a small amount of manganese dioxidein a graduated cylinder will produce copious lather on addition of asolution of hydrogen peroxide.45. Aluminum powder mixed with iodine will ignite when a drop of wateris added. (care with vapor)46. Show that the wetting property of water is increased with theaddition of detergents by filling two cylinders with water, one havinga detergent added. Place a piece of wool yarn, or non-absorbentcotton ("ducks") , on each surface and observe the time required forthe wool to sink.47. A chemical garden can be grown in a solution of 150 mL of water inwhich 35 mL of sodium silicate has been dissolved. Growth will startwhen crystals of compounds containing colored ions such as Cu, Co, Ni,Fe, and Al are added to the solution.48. A model of a Bunsen burner made from a three-foot piece ofone-inch glass tubing is excellent for class demonstrations ofstrike-back gas-air mixtures, flame structures, etc. Mount a largeglass tube vertically on a stand. Fit the bottom of the tube with aone-hole stopper equipped with a small glass tube for injection of thegas. Light the burner adjusted for a rich mixture of gas and adjustcork for other affects.49. Zinc powder mixed with ammonium nitrate will produce voluminouswhite smoke when ignited at arms length with a Bunsen burner.50. The patriotic colors are produced by pouring sodium hydroxidesolution into three beakers containing one each of the followingsolutions; phenophtalein, lead acetate, and copper sulfate.51. Lead ions combined with iodide ions produce plumbous iodide which,when washed and recrystallized from hot water, produce interestinggolden crystals.52. Antimony trichloride is not soluble in water but will dissolvewhen chloride ion concentration is increased by adding concentratedhydrochloric acid. Diluting the solution with water precipitatesantimony oxychloride and again concentrated hydrochloric acid will putit back in solution.53. Most solids are more soluble in hot water that in cold water.Calcium acetate is a common exception to the above, showing negativesolubility , and is precipitated out when its water solution isheated.54. When explaining conductivity, ionization, and their relation,remember that hydrogen chloride (HCl) does not show ionization inbenzene, nor does it conduct an electric current. In water, HClbecomes an excellent conductor. Glass does not conduct electricityexcept when hot, plastic, or molten. Try it with 115 voltconductivity apparatus.55. The effect of heat treatment and tempering of metals can bedemonstrated by heating bobby pins to redness in a Bunsen flame. Dipone heated pin in cold water to chill. Allow the other pin to coolslowly. Compare these pins with one that has not been heated bybending each one.56. Chemical reaction between gases under water can be shown bybubbling acetylene gas and chlorine gas into water in such a mannerthat the bubbles come in contact before they surface. As a suggestionfor better viewing in the reaction, fit a glass tube with a two-holestopper to make the apparatus.57. The difference in degree of solubility of a solid in variousliquids can be demonstrated by carefully pouring carbon tetrachloride,water, and ether into a cylinder to layer them. A few crystals ofiodine dropped through the layers will dissolve as they fall throughthe different layers. The degree of color in the liquids willindicate the amounts dissolved.58. Combustibility of certain dust particles in air can be vividlydemonstrated by placing corn starch in a handkerchief or cloth bag anddusting through the cloth mesh into a flame. .... or put some powderin the end of a piece of glass tubing and blow this into the flame.Messy!59. Spontaneous ignition results when glycerin is dropped on a smallheap of potassium permanganate. Magnesium powder along the edge addsto the spectacle. (protect desk top from splattered particles) ....worked for us only with KMnO4 ground in a mortar with pestle.60. When it is desired to collect the hydrogen displaced from water bysodium metal, it is sometimes difficult to get the metal under waterand into the container without unwanted incident. The sodium metalcan be pinched closed with tweezers and inserted in the collectingcontainer where it will surface without carrying air.61. Carve a spoon mold in wood and fill with molten Wood's metal. Thespoon will melt in hot water, coffee, or tea. Save the mold to recastthe spoon as part of the demonstration.62. Sometimes there are times you wish to etch glass. Other thanusing sandblasting, you may use hydrofluoric acid, but this is nastystuff to keep around. Dissolve about 72 grams of sodium fluoride and14 grams potassium sulfate in water for one solution and 28 grams ofzinc chloride and about 130 ml. of hydrochloric acid in 130 ml ofwater for the second solution. Mix only a small amount of thesesolutions together and use a brush or pin to paint the glass. It willgenerate hydrofluoric acid and should etch the glass in about half anhour.63. In digging through Henley's formulas, I found this formula forgunpowder. 75 grams potassium nitrate, 15 grams charcoal, 10 gramssulfer. You might mention that gunpowder is not an explosive unlessit is under pressure. Gunpowder won't even burn in a vacuum ifignited with a red hot platinum wire.64. Here is a recipe for that "old time" flashpowder for photography.6 grams powdered magnesium, 12 grams potassium chlorate. Mix lightlywith a wooden spatula with care. You can ignite the powder byapplying flame or placing it on wax paper and lighting the paper.Only use about 1 gram of this powder and it is best to only make asmuch as you will immediately use. It's not safe to store.65. Here is another recipe for flashpowder. Take the same precautionsas stated in 64. 4 grams powdered aluminum, 10 grams potassiumchlorate, 1 gram sugar. All these powders are smokey, but some smokemay be trapped by hanging a wet towel over the powder to catch thesmoke cloud.66. A glowing picture can be made out of this "invisible ink". Mix 40grams of potassium nitrate and 20 grams of gum arabic in 40 ml ofwater. You can use an old writing pen or brush to draw your pictureor message being sure that all lines connect. If you trail a lineover to the edge of the paper and let this dry, you can hold a matchto this spot and watch the ink start to glow and scorch the paperunder it. Hopefully your art won't all go up in flames67. Interesting crystal patterns can be shown by dissolving a smallquantity of dextrin (gum arabic and tragacanth are not so suitable) inan aqueous salt solution as concentrated as possible, for instance, inmagnesium sulfate, or zinc sulfate or other salt. Filter thesolution and coat glass plates evenly with the filtrate. Leave themlying horizontally until the water evaporates. The crystals should bedifficult to remove and are very intricate, like frost.68. In 61. there is talk of Wood's metal. You can make some bymelting 2 parts tin, 4 parts lead and 5 to 8 parts bismuth. It willmelt around 151 to 162 degrees F. Another recipe calls for 7 to 8parts bismuth, 4 parts lead, 2 parts tin and 1 to 2 parts cadmium.This will melt at around 158 degrees.69. Some brave soul may want to try this. Get a beaker of ethanol- agood source might be Everclear, not denatured, and ignite it. You candip a banana into the burning alcohol and eat it as it burns. Thefire will go out in your mouth.70. A hot water bottle that demonstrates heat generated by the heat offusion can be made as follows: mix sodium acetate and sodiumhyposulfate in the proportion of 1 part acetate to 9 parts hyposulfateand fill a bottle or beaker about 2/3 full of the mixture and place itin hot water or in the oven until the salts melt. Be sure to seal thebottle as well. The bottle will radiate heat for at least a half aday or until all the salt solidifies. Shaking the bottle will renewits heat-giving properties.71. A simple heat pipe can be made with copper tubing sealed at oneend. Put water in the tube and along cotton wick and seal the otherend. When the tube is placed in a flame with one end down, the upperend should warm up much faster than a tube with no water in it. ...This can also make a very good bomb, not recommended. Freon or someother liquid with a low boiling point might be used.72. To make methyl salicylate (oil of wintergreen), put about 1 gramof salicylic acid on an evaporating dish and add to it 1 ml ofmethanol. Next, add 3 drops of concentrated sulfuric acid and warmgently. You should be able to identify the odor.73. To make aspirin, prepare a water bath by heating a 400 ml beakerabout 2/3 full of water and bring it to a boil. To a conical flaskadd 6.00 g. of salicylic acid and add about 8 ml of acetic acid.Swirl and place in beaker of boiling water for about 15 minutes oruntil solid dissolves. Remove from boiling water and cool underrunning tap water. Add about 25 ml of ice water and set flask in icebath until crystallization appears complete. Filter crystals fromliquid. Purify crystals by dissolving in 20 ml of ethanol in a 100 mlbeaker. Warm if crystals do not dissolve completely in a warm waterbath.. Next add 50 ml of warm water to solution and set in ice bathto speed cooling. Filter out the aspirin crystals. 100 percent yieldshould give 7.82 grams of aspirin.74. Equip a flask filled with water with a two-hole stopper having aglass tube reaching the bottom of the flask and drawn to a nozzle atthe other end in one of the holes; in the other hole place a longglass tube with a thin bulb filled with ether on its submerged end.Seal the top of the ether tube. When the bulb is broken inside theflask, the ether vapor will force the water from the nozzle.75. Solubility of ammonia gas is quickly demonstrated by putting fivemL. of ammonium hydroxide in a 500 mL flask equipped with a one-holestopper, glass tubing drawn to a nozzle on one end and attached to along heavy rubber tubing. Heat the flask and ammonium hydroxide untilammonia gas comes from the open end of the tube. Place tube end inwater and await action.76. Fill a Coca-Cola bottle with two parts hydrogen gas to one partoxygen. Stopper and wrap bottle with cloth or tape. Hold bottlebottom against chest and bring lighted match to mouth of bottle whileremoving cork. The sonic boom is in the order of 3-5 electron volts -had it been a nuclear reaction, instead of chemical, the explosionwould have been on the order of 212 Mev. and much louder. .... takecare with this one, possibility of flying glass!77. Magnesium burns in water! Prepare a test tube by blowing a smallhole near the bottom. About one inch up the tube from its centerplace a coil of magnesium ribbon. Fill the test tube about half fullof water, stopper and invert so that the water does not touch ribbon.Heat top layer of water to boiling; then heat water and ribbon rapidlyuntil ribbon ignites. Ignite hydrogen gas as it comes out of the holein the test tube.78. Catalytic oxidation of methyl alcohol can readily be accomplishedby suspending a heated coil of platinum wire in a partly coveredbeaker of methyl alcohol. The product is recognizable to biologystudents as formaldehyde.79. Effect of gas density on sound can be demonstrated by fillingseveral balloons with different gases such as air, carbon dioxide,natural gas, helium, propane, etc. to about the same pressure. Fix awhistle to be blown to a short piece of glass tubing. Note the pitchas gas from the different balloons blows the whistle.80. Conservation of energy -- support a heavy pendulum from ceiling,draw back against nose, with your head against the wall. Releasependulum bob and stand nonchalantly awaiting its return. It cannotrise to greater than height from which it started. You are save ifyou do not move!81. A simple cloud chamber can be made from a gallon jug fitted with aone-hole stopper with a short piece of glass tubing. Blow into thejug through the glass tubing to increase pressure. Put finger overend of tube and pull stopper, suddenly reducing the pressure. Nocloud is formed. If a lighted match is dropped into the jug and theperformance repeated, a cloud will form.82. Prepare a soap bubble solution in a shallow dish or pan. Fill aballoon or beach ball with a 2 to 1 mixture of hydrogen and oxygen.Using a small nozzle delivery tube, blow the gas mixture from theballoon through the soap solution to produce copious bubbles. Pick uphandful of bubbles and holding them far out in front of you, ignitewith match. The explosion will not be felt by you; however, someonestanding too near may have an ear injured. .... sound is indeedintense. We did this in a long hall & got good reverberations.83. Call this tubeless television. Project a lantern slide with a fewsimple words (i.e. That's All) cut in a piece of metal foil so thatthe image is in mid-air. Direct the beam of lantern out through opendoor so that it does not attract attention. Wave a white wand in theplane of the image. Persistence of vision creates a complete image,apparently materializing in space.84. Singing flame variation. Hold a four foot 1 - 1/2 inch glass tubeperpendicular. Have inserted in the bottom end at a predeterminedresonance point a heavy disc of wire gauze. Heat the wire gauze withburner, remove flame and hear a phenomenon.85. Fill a large cylinder with carbon dioxide. Float a soap bubble onit. When done in perfectly still air, explain what you see.86. Catalytic oxidation of ammonium hydroxide is spectacular. Suspenda coiled platinum wire in an English graduate just above the surfaceof some ammonium hydroxide. Bubble a fine jet of oxygen through theammonium hydroxide. Violent explosions! ... not for the faint ofheart. .... I like a small coil of Pt wire above conc'd NH3 in a smallErlenmeyer. Glows for hours.87. Sometimes it helps to point out that the sine of a triangle is theopposite over the hypotenuse; O/H, oh!. The cosine is "ah". Anothermethod is "Chief Sohcahtoa" or Sine is opposite over hypotenuse,cosine is adjacent over hypotenuse, tangent is opposite over adjacent.88. Activation of nucleus to fission may be demonstrated by catching asoap bubble between two wire rings with handles. When caught,puncture the top and bottom areas leaving a cylinder between therings. Carefully pull the rings apart, noticing the shape of thefilm, until it breaks in two films over each circle.89. Place a copper penny on glass slide on micro-projector. Putsilver nitrate solution around copper and watch silver crystals formon screen. Note many peculiar characteristics they exhibit.90. Build a rotating platform from front-wheel and spindle ofautomobile. Rigidness, coupled with small friction and small play inbearing is amazing. This is useful to demonstrate rotational inertia.91. Action and reaction. Place plank on rollers (doweling). Mountmassive load on small cart on plank. Attach rubber bands to plank andcart, stretching and tying back with thread or sting. Burn tread torelease system. Road goes one way, cart goes another.92. Show action and reaction by standing on rotating platform andswinging a baseball bat vigorously at a pitched ball. .... This shouldbe amusing- I'd do it outside of course.93. Turn around by swinging baseball bat in circles over head.Reversal of swing reverses motion of body. (Standing on rotatingplatform.)94. Again on the rotating platform, pirouette. Hold heavy weights atarm's length, have someone rotate you slowly. Bring weights close tobody. Explain the marked increase in speed.95. Weld bicycle axle nuts in end of iron pipes. Screw the pipes onwheel axle for handles. This makes an excellent gyroscope; betterwhen the rim is weighted by winding it with iron wire.96. Holding gyro axis horizontal, stand on the rotating platform.What happens when the axis is rotated to a perpendicular position tothe right? to the left?97. Fix six or seven metal nuts on a string at distances in proportionto 1/2 gt2 where it is 1, 2, 3, 4, etc. Hold string perpendicular andstill and let drop. Note there is no difference in the time intervalsas nuts strike the floor.98. Cover the bottoms of two beakers with gasoline in one and kerosenein the other. With asbestos squares for covers to beakers handy,pitch lighted match into the gasoline. Smother flame with asbestossquare and repeat procedure with beaker of kerosene. Heat keroseneand try again. Do not heat the gasoline!99. Tune two metal dog whistles to unison or absence of beats. Heatone whistle with flame. Beats reappear as pitch of heated whistlerises. (please don't burn your lips!)100. Into a small box, place small objects and seal box closed.Students can examine box, blindfolded, and tell you: (a) How manypieces are in the box. (b) the shape of the pieces. (c) How heavy thepieces are (density). (d) How big the pieces are. (e) The color of thepieces. By doing this the student has reason to believe that thescientists may know something about the atom even though it has neverbeen seen; as he has not seen the objects in the box.101. Drill a brass rod for a screw in one end. Insert screw abouthalf way. Balance rod at its center on a pivot. Throw off balance bymoving small screw on one end. Heat on end of rod and it will come tobalance again.102. Units of work can be visualized with this device. Mount on asingle base two pieces of 2x2 inch wood, one 12 inches long and theother slightly over 9 inches long. Using a pound weight, lifting itfrom the base to the top of the one foot tower represents one footpound of work. Lifting the weight to the top of the 0.76 foot towerrepresents one joule of work. A penny lifted from the table top on toa piece of paper laying on the table represents an erg of work. Thenext unit electron volts, is 1.6 x 1023 erg.103. Heat of oxidation is evident when a piece of aluminum foil iswrapped around the bulb of a thermometer and the preparation immersedin HgCl2 solution.104. There are many invisible inks. Write with solutions of thefollowing chemicals and develop as indicated: AgNO3 - light; CoCl2 -Pb(C2H2O2) - H2S; Co(NO3)2 - oxalic acid; Starch - iodine; CuSO4 -NH3.105. Let the student explain why one can pick a coin from the bottomof a beaker of water which has been dusted with lycopodium powder andnot wet a finger.106. Bubble CH4 through a solution of H3BO3 in CH3OH in a flask fittedwith a two hole stopper. Insert a Y-tube in the other hole of thestopper and attach to one arm a Bunsen burner. To the other armattach a drying tube filled with activated charcoal, then to a bunsenburner. Light both burners and explain the difference in flame color.107. Place a slug of pure Zn in dilute H2SO4 and note thatpolarization prevents the continuing of hydrogen evolving. Attach asmall platinum wire to the slug and again place in acid. The zincwill now be completely consumed. Why do the bubbles come off theplatinum?108. The solubility of calcium butyrate decreases with increasingtemperature, unlike most compounds.109. Place equal amounts of calcium carbonate solution into twocylinders. Buffer one cylinder with a sodium acetate solution beforeputting equal amounts of two normal (2N) acetic acid into each.Explain the difference in the rate of reaction.110. Collect ammonia over mercury. Allow a single drop of water orCuSO4 to rise through the mercury to the gas. Explain the absorptionof the gas in each.111. Prepare a tincture of iodine and potassium iodide. Place a dropon a microscope slide and project on a screen with a microprojector.The heat from the lamp will produce beautiful color andcrystallization effect.112. Use K2Cr2O7 as a catalyst in KClO3 instead of the usual MnO2.Less is required.113. When copper and cobalt ions are used to harden water, the ionexchange area is visible in a zeolite column. Copper and cobalt areanalogous to magnesium and calcium in most natural hard water.114. Lenz's Law may be demonstrated with any toy wheel of nonmagneticmaterial and low friction attached to a convenient holder. Wheelshould have spokes for clearest understanding. Spin wheel in air thenbetween poles of a reasonably strong horseshoe magnet. Spokes cutlines of force, induced current field opposes motion.115. Student feels heat of hydration when a small amount of anhydrouscopper sulfate is placed on hand and a drop of water is added to it.The heat involved is large. Have water ready to cool off the hand.116. Alcohol, carefully floated on concentrated sulfuric acid in atest tube exhibits flecks of fire at the intersurface when potassiumpermanganate crystals are allowed to fall through the liquids. ....this also is spectacular , particularly with small groups of students.Write the equation.117. Natural acid-base indicators can be had in such common foods asblue-berry juice, red cabbage, carrot, beet, etc. Determine over whatrange of pH they operate.118. Paper chromatagraphy can be quickly demonstrated by placing aspot of most any ink near one end of a a strip of filter paper whichtouches water.119. Find the center of gravity of a stick held horizontally acrossthe fingers of both hands. Center of gravity will be at the pointwhere the fingers come together.120. Mark the center of gravity of a hammer with a spot of paint.Toss the hammer into the air with a spin and note that the spot is themost stationary point.121. Clamp an iron rod to a broom handle near its center. Hold broomhandle in both hands with rod extended horizontally. Attach a weightat different distances from the handle and note how torque increases.Lever arm has real meaning here.122. Show conservation of energy in a swinging pendulum by noting thatit returns to the same level each time. Place an obstruction belowthe point of rotation so that the arc of swing will be changed.Change the obstruction to a point one half the distance between thelowest and highest levels and again below this point. Explain why thebob loops over the obstruction.123. Evidence that one may see the sun below the horizon can bevisualized by looking at a penny in a bowl filled with water. Notethat the penny cannot be seen over the rim of the bowl unless there iswater in the bowl. When the bottom of the sun appears at the horizon,the entire sun is actually below the horizon, refraction isresponsible.124. Select two test tubes so that one barely fits inside the other.Partly fill the larger with water and float the smaller one on thewater. Invert tubes and see the water spill out of the larger, butthe smaller tube fills up.125. A coiled platinum wire suspended from a rubber stopper in a flaskfilled with ammonia gas and air will glow for about ten minutes. Blowover the mouth of flask to replenish oxygen. .... see also #86. Useconc'd NH3 solution and with the top open to air.126. Place an object on the bottom of a metal pan so that its shadowmay be measured. Fill the pan with water and remeasure shadow.Refraction is evident if pan, object, and light source are keptstationary.127. Attach one lead from a spark coil to foil surrounding a glasstube of about one-inch diameter. Extend a wire from the otherterminal of the spark coil through the tube, insulated from the foil.Place a small amount of hydrochloric acid in one flask and someammonium hydroxide in a second flask. With glass tubing connect theflasks and large glass tubing in train. Blow air into the first flaskcausing ammonium chloride to be forced into the Cottrell precipitator.Activate spark coil and see 'smoke' consumed. .... we used to have oneof these in the dept; it worked near instantly on cigarette smoke.128. Dissolve a few crystals of cobalt chloride and potassiumthiocyanate in a graduate one-third full of ether. Add and equalvolume of water to separate red and blue colors. A few drops ofsilver nitrate solution in the mixture completes the patriotic colors.129. Interesting intermittent explosions and flame travel can bedemonstrated by placing a four-foot by one and one-fourth inch glasstube in a vertical position with a lighted burner at the top and asource of methane gas induced at the bottom.130. Cut three discs from plywood; diameters about eight to twelveinches. Cut a three inch circle out of the center of one piece andanother circle of the same size within an inch of the outsidecircumference. Remove the intervening wood between tangent lines tothe circles. Make a lead disc to fit the slot and sandwich the piecesbetween the other discs. When thrown into the air it can be made torotate smoothly about its geometric center or about another center ofgravity in an eccentric manner. It can also be made to rum up anincline, or down and then reverse to roll up. The same apparatus canbe made with cardboard and a half-dollar.131. Have students move around the room as sun, moon, and earth toshow effects of rotation, revolution, tilt of earth on axis, etc.132. A burning match head pressed against a silver coin shows directcombustion between sulfur and silver. Also, a hard-boiled egg yolkand silver coin gives the same result. .... the trouble is trying tofind a silver coin nowadays.133. Suspend a bar magnet on a string. Rotate another magnet under itto show transfer of magnetic energy. What changes the direction ofthe poles? How can the change be effected without human movement.134. Carry a glass brim full of water up a ladder and press it to theceiling. Ask the "sucker" to push against the bottom of the glasswith a long pole while you climb down and put away the ladder and goon about other business. If the ceiling is smooth, the student neednot fear that the glass will fall.135. A Cartesian diver can be made with a Coca-Cola bottle full ofwater and a match head. Keep breaking off the match stick until thehead barely floats. Thumb pressure on the mouth of the bottle makesthese little divers zip up and down in the bottle.136. Flame analysis can be done without the expensive platinum wireand without the necessary cleaning before each test. Dissolve a asmall amount of salt to be tested in a few milliliters of alcohol.Ignite the alcohol in a clean dish and notice the color. .... I dothis with the alcohol for alcohol lamps as a safety precaution sincealcohol lamps flames are nearly invisible.137. Set up a long glass tube filled with water and containing a testtube as a Cartesian diver to operate with a squeeze bulb. Theapparatus can be used for demonstration of principles of Archimedes,Pascal, and Boyle.138. A relatively cold flame may be produced by igniting a mixture ofcarbon tetrachloride and carbon disulfide ( or watered alcohol). Onpreparing the mixture, first prepare a mixture with too much carbontetrachloride (or water) so that the mixture will not ignite. Add asmall quantity of carbon disulfide to a portion of the mixture andtest it for the right temperature. A handkerchief may be dipped inthe mixture and held in the hands while burning if it is kept moving.139. To demonstrate Bernoulii's principle, cut a circular piece ofcardboard slightly larger than the end of a thread spool. In thecenter of the circular cardboard, push a straight pin to the head.Set the spool over the pin point and down on the cardboard. Blow inthe other end of the spool. The cardboard will cling to the spool aslong as there is air motion through the spool.140. Cut a four inch piece of wire from a coat hanger. Bend one halfinch back on one end so that a leather belt will slip in the hook.Support the other end on finger and belt will hang in space as on "skyhook" .141. Select a large spool and wrap several turns of ribbon or twinearound it. With the spool on a flat surface and the ribbon coming upfrom underneath, by pulling on the ribbon at different angles to thesurface, applications of torque, friction, and motion can bedemonstrated .142. Submerge a beaker in a glass container of water filling thebeaker with water. Invert beaker to upside-down position under water.Invert another beaker and submerge so that air is trapped in it. Pourair from one beaker into another, pouring up. Note fluid nature ofthe gas.143. Fill a flask two-thirds full of water and bring to a boil. Corkthe flask and invert. Place ice cube on bottom of flask and see waterbegin to boil again. If the flask is corked with a one-hole stopperwith a glass tube extended almost to the bottom of the flask, boilingcan be effected by reducing the pressure of the entrapped air. Youcan also run cold water over the flask. Have the student feel the"hot" flask of boiling water.144. Wave motion and standing waves can be demonstrated by attaching astring to most any small electric motor or vibrator. An electricshaver is ideal. Hang weights of varying amounts on the string tochange wave length and frequency.145. Copper sulfate solution poured over Dowex 50X resin loses itscolor through ion exchange. Sodium chloride solution poured over theabove resin removes the copper sulfate and the effluent is againcolored.146. Mix sand and lead oxide for an ore. Put mixture in a test tubewith water and mineral oil and shake well. Note the separation of themineral and point out "the gangue's all there". ... but how manymodern chemistry students know what "gangue" is ???147. Prepare two small whistles with a screw in the end so that thelength of the air column can be adjusted for different frequencies.Attach the whistles to a Y tube so that they can be blownsimultaneously. Not that when the pitch of one is varied a low pitch"beat note" may be heard rising or falling in pitch.148. Suspend a water faucet above a sink by a wire only. Water can bemade to flow in a strong stream from a faucet even though the faucetseems to have no connection with a water supply. A glass tube fromthe water source is inserted into the faucet so that the water fallingabout it conceals the tubing and the fact that it carries the water upto the faucet.149. A wooden slat is covered with a newspaper except for a few incheswhich project beyond the edge of a table. The protruding slat isstruck by a bat and it breaks instead of tearing the paper.150. An object or person may be weighted by hydrostatic pressure. Usea hot water bottle with a stopper fitted with about two meters ofrubber and glass tubing. Fill the bottle with water and connect thetubing so that it extends vertically. Stand the person or object on aboard of known area touching the bottle. The area squared times thepressure will equal the weight. Pressure is the height of the waterin the vertical tube above the bottle times the density of the water.151. Set a lighted candle in the center of a battery jar or other widemouth glass container. Fill another jar of about twice the capacitywith carbon dioxide gas and proceed to pour it into the one with thelighted candle. A soap bubble carefully placed in a jar of carbondioxide will float in the center. ... this does work. Can make CO2with Na2CO3 or NaHCO3 + H2SO4152. Put equal quantities of water in two small beakers. To each addone of the following chemicals in equal amounts. Barium oxide isexothermic while ammonium nitrate is endothermic. Pass the beakersaround for inspection.153. The force of normal external air pressure is sufficient tocollapse a rectangular varnish can. In a clean can place a fewtablespoons of water and bring it to a boil to expel the air with thewater vapor. Close the cap tightly as soon as water boils vigorously.Cool the can by dashing cold water on it. ... two comments: Youdon't need to run cold water over the can. Be sure to stopper it verysoon after you remove the source of heat. If you don't, the reverseeffect happens.154. Wash freshly cut lead shavings with distilled water. Pour thewater through a resin ion exchanger and develop by the usual methods.155. Let two boys with egg beaters beat oils of different viscosity.The boy having to beat the heavy oil will tire first.156. Suspend a coiled platinum wire just below the lip and inside anEnglish graduate containing a few milliliters of ammonium hydroxide(concentrated). Bubble oxygen through the ammonium hydroxide.Violent explosions occur. ... I don't even know what an Englishgraduate is!157. Cotton or filter paper saturated with turpentine and put into aquart fruit jar or wide mouth bottle of chlorine gas willspontaneously react. Have jar cover handy to prevent soot fromcovering the room.158. Scrape clean two one-by three inch strips of lead and submergethem in a 5 N solution of sulfuric acid. Charge the cell byconnecting the strips to a three volt battery for a couple of minutes.Discharge by connecting the cell to a bell or light bulb.159. A copper strip or wire suspended in a silver nitrate solutionproduces a silver tree by the replacement action.160.A dry plastic sponge can be measured for volume. Ask how muchwater you can pick up with it. When wet, it may pick up more than itsinitial volume. It expands slightly and is mostly a "lot of air holesfastened together."161. Arrange wood matches closely on a soft board by means of straightpins placed through them at their midpoint. Hold the board uprightand ignite the bottom match. The others will follow in turn todemonstrate a chain reaction.162. Three students each holding a rod of a different substance in aflame, will demonstrate the difference in conductivity of heat bytheir object from the flame. Use about the same sized rods of iron,aluminum, glass, copper.163. Colored crayon marks on white paper viewed through colored platesof glass shows color filter. Make a drawing of a bird in a cage withappropriate colored chalk and let the bird out of the cage by viewingthrough colored glass.164. Games can make both learning and instruction a pleasure. Buildpuzzle of jumbled letters for other students to solve. An example: REGICAL--great ice sheet A- Glacier ISOSFSL--Trace of past in rocks A-Fossils165. Show properties of air by bursting paper bag filled with air,upsetting brick by blowing up bag, drop sheet of paper horizontal thenon edge, put paper over tumbler full of water and invert, etc.166. Some properties of water make interesting conversation pieces.Demonstrate that ice is lighter than water by placing large icicle inmilk bottle (ice cubes may be used). Add cold water to fill jar whileholding ice under the water. Let ice float and observe what happensas the ice melts.167. The effect of tobacco smoke on fish can be demonstrated byarranging a train of two flasks, each filled with water and onecontaining a fish. A cigarette is smoked through the water containingthe fish by siphoning water from the other flask.168. Heat strongly some protein in a test tube having pieces of litmuspaper and lead acetate paper over the lip. Blackening of proteinshows its carbon content; litmus turns blue, indicating ammonia; leadacetate paper turns black, indicating the presence of hydrogensulfide; water condenses on side of the test tube.169. Moth balls rolled in sodium bicarbonate and put into a cylinderof very dilute hydrochloric acid will rise and fall with regularity.170. Print with capital letters such words as CHICK BOX or FIRSTCHOICE. Place a mirror over the top half of the words andperpendicular to the plane of the paper and observe the reflected partof each word with that visible. ... we've done this one with thewords Titanium dioxide (all in caps) with one of the words in blue,the other in red, with a large cylinder of water in front of it.Students speculate for almost hours on whether it's the liquid, or thecolors or just what. A very interesting one.171. Heat a spot on a cold light bulb with a blow torch and a dimplewill form in the glass. Light the bulb and again heat a spot until apimple forms.172. An interesting conversation piece can be made from a salt box.In the center of one end punch one hole with a sharp needle. Aboutthe center of the other end punch three holes at the corners of anequilateral triangle about two millimeters apart. Look through theone hole and see the three holes. Look through the other end at theone hole and explain what is seen. Label the box "Drunk-O-Meter" andlist the following directions: 1 hole-sober, 2 holes-nippin, 3holes-dog drunk, 4 holes or no holes at all -dead drunk.173. Exhaled air still contains considerable oxygen. Show that aburning match can be withdrawn from the mouth still lighted. Forcewater from a bottle with exhaled breath and show that the air willsupport combustion by burning a candle in it.174. The burning of a wood match shows among other things, destructivedistillation, burning of a gas, and burning of a solid at the crimpedend after the flame disappears.175. Properties of alpha, beta, and gamma rays may be demonstrated bypropping a smooth board of about eight inches by twelve inches on anincline and arranging a bin with a trap gate at the top so that threedifferent sized balls can be released to roll down the board. Place astrong magnet below the board and just to one side of the gate. Notehow each falling ball goes into a separate bin because of the amountof deflection. The gamma may be represented by a brass or aluminumball, the beta would be the smaller of the steel balls.176. To demonstrate center of gravity outside of a body and thecriterion for stability, borrow two pocket knives from students. Pushblades firmly (but carefully) into a pencil near the sharpened endwith the handles beyond the point of the pencil. Balance it pointdownwards on your finger. If the center of gravity balls below thepoint of balance, the system will be stable.177. The stabilizing action of colloids is a principle utilized in the"Foamite" fire extinguisher. Into each of two tall cylinders orhydrometer jars pour a solution of sodium bicarbonate. Add a teaspoonof licorice extract to one. Add aluminum sulfate solution to each andnotice how carbon dioxide bubbles subside rapidly in one while foamrises over the top of the other container and spreads.178. Bernoulli's principle can be shown by balancing an inflatedballoon or beach ball on a jet of air from the output end of a vacuumcleaner. The balloon will hover near the ceiling and will not falloff although tipped at a considerable angle. A ping pong ballbalanced on a fine jet of water will illustrate the same.179. Many organic substances, dead or alive, show interestingcharacteristics under black light. Cockroaches are multicolored underultra-violet light.180. For a quick demonstration of colored flame, ion color, or burningof metal, keep salt shakers filled with powdered metals such as iron,aluminum, magnesium, zinc, and antimony. Dust these into a bunsenflame. Salts of strontium, lithium, barium, copper, and sodium can besprinkled into a flame by the same method.181. Pour copper sulfate solution over coarse iron fillings on afilter paper. The blue solution on coming through the filter will becolorless. If a small amount of acid was placed in the collectingcontainer, when the solution is poured back through the filter, itwill again be colored.182. Ionization in a flame can be shown by holding a lighted matchnear a charged electroscope. Charged pith balls or balloons losetheir charge rapidly when a flame is brought near.183. Light rubber balloons suspended from long silk strings act asdemonstration electroscope when charged by rubbing with woolen clothor fur. Individual balloons can be made to stick to flat surfacessuch as walls or ceilings by rubbing then on clothing.184. Cut a six inch circle of plywood or press board. Cement a smallcork at its center, Drill a very fine hole through the disc and cork.Inflate a balloon and fasten its mouth over the cork. Place theapparatus on a smooth surface to see almost frictionless motion oncushion of air.185. There are three steps to the functioning of the human mind: a.Observation b. Incubation c. Illumination. People stumble over morefacts in a day than they see in a lifetime and meditate on little ofthat which they perceive, yet, enjoy ultimate satisfaction onattaining any degree of the final function.186. Mnemonics are useful memory devices and should be used withemphasis on the facts rather than on the device for remembering.CREAM may mean the five kinds of energy: Chemical, Radiant,Electrical, Atomic, and Mechanical.187. Analogous inference, although not true or real, may be a hitchingstar for some philosophy that affords a solid foundation for work. Atriangle can be used to show relative importance of study andapplication to one's future. What you "is" today determines what you"was" from any future date. Both what you "is" and what you "was"determine the length of you "will be" on a future base line.188. Rubber bands or strips can be tied together in bundles andcharged by stroking with fur or by other means. A lighted match nearthe repelling strands will cause them to collapse.189. A dust explosion may be made from a syrup bucket or any can witha tightly fitting friction lid. Punch a hole in the bottom largeenough to admit the small end of a funnel. Attach a length of rubbertubing to the extended funnel. Place a single thickness of Kleenex inthe funnel to support a teaspoon of lycopodium powder. Place asix-inch lighted candle on the opposite side of the can from thefunnel. Close the lid firmly and give a quick puff on the rubbertube. The lid usually hits the ceiling.190. A straight metal blow pipe connected to a gas supply is fixed inan upright position on the demonstration desk and lighted. A thirtyto sixty centimeter glass tube of large diameter is lowered over theflame until at a certain position a sound is heard.191. Done with a lot of flourish, this brings down the house! Themechanics of friction, forces and inertia involved make interestingconversation. Set a glass two-thirds full of water about three inchesfrom the edge of a table. On the glass place a pie tin. On the pietin and directly over the glass place a a spool on end. Place an egg(fresh if you are confident) on the spool. With one foot on thebristles of a springy broom, pull back the handle and aim at the pietin. The spool rolls on the table, the pie tin scoots to the floor,the glass and the water remain unmoved on the table with the eggunharmed in the water.192. Blow or suck on the small end of a funnel containing a ping pongball. The ball will not fall out even though the funnel is inverted,so long as air is moving between the ball and the funnel wall.193. Look through a paper tube at some distant object with the righteye while holding a book over the other eye and close to the tube. Itwill appear that one is looking through a hole in the book.194. Draw a circle in the center of a piece of white paper withcolored crayon. Stare at the circle at arms length for a time, thenlook at a blank wall. A circle of some other color appears on thewall.195. A ten gram ball can be made to lift a thousand gram object. Thetwo are connected by a strong string passing though a six inch lengthof glass tubing with both ends carefully fire polished. The glasstube is held perpendicular in the hand and the ball is rotated to liftthe weight. Proof of AMV2/2 is possible to 3-4% if radius and angularspeed are measured.196. Swing a lighted neon bulb rapidly to show sine curve in space asalternate deltas glow.197. Boil water in a paper cup. The paper will not burn until thewater has boiled away.198. Considerable heat is generated in stretching a rubber band. Holdthe band against the upper lip and extend it quickly. Allow therubber band to contract rapidly and note that it absorbs heat.199. Stretch a rubber band tightly and rub against an electroscope.Determine the nature of charge produced.200. Combing the hair near the aerial of a radio produces static.201. Suspend thermometers inside and outside a large closed bottle toobserve the hothouse effect. The same effect can be observed bymeasuring the temperature inside a closed automobile and the outsidetemperature.202. Demonstrate the nature of percolator action with a glass funnelinverted in a beaker of water that is being heated.203. Float a needle or razor blade on water by aid of its surfacetension. Weaken the surface tension with a speck of detergent. ...one can also magnetize the needle beforehand and have a compass.204. Scrape flecks of gum camphor on to a water surface and see thepieces propel themselves over the surface. A drop of olive oil on thesurface stops the action.205. Mount a pendulum on a


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