00:00:00 Hello, I am Harry Sello. It is my pleasure to introduce Tempest in a Test Tube, a television show which made its debut August 24th, 1955, on KQED Channel 9, the educational station for the San Francisco Bay Area.

00:00:20 Tempest was a series of 53 half-hour shows pioneering a new approach in which I as lecture demonstrator gave live, unrehearsed presentations of a series of chemical experiments.

00:00:35 These were designed to illustrate basic, simple chemical principles.

00:00:41 The purpose was to stimulate an interest in chemistry by teenage students and by adults.

00:00:48 The talks and experiments had to be entertaining, educational, and simple.

00:00:54 Spontaneity and liveliness were key to the approach.

00:00:58 All the experiments used in the shows were designed and constructed by members of the California section of the American Chemical Society.

00:01:07 The participants were employed by the Shell Development Company, Emeryville, and by Chevron Research, Richmond.

00:01:15 A grant of $52,000 from the Ford Foundation and National Educational Television permitted the filming of the first 24 shows of the series.

00:01:26 The management for the ACS consisted of Alan Nixon, section chair, Fred Strauss, TV committee chair, myself as first emcee, and Aubrey McClellan, second emcee.

00:01:40 We four constitute the core of the present committee.

00:01:45 The series was extremely popular then with KQED viewers of all ages.

00:01:53 The senior chemist committee of the California section today is determined to revive Tempest for the benefit of elementary schools,

00:02:03 high schools, adult education classes, ACS local sections, historical archives, TV stations, and similar organizations.

00:02:13 We believe in chemistry as a second language.

00:02:19 While basic principles have not changed, practices have.

00:02:24 Forty-five years ago, such simple chemical demonstrations were not treated with the degree of safety considerations that they are today.

00:02:33 Today, even such simple demonstrations would be carried out with the proper regard for safety glasses, shields, protective gloves, laboratory coats, and visible fire extinguishers.

00:02:48 The principle of safety first would be explicitly present as part and parcel of a modern Tempest in a test tube.

00:03:03 Thank you.

00:03:33 Tempest in a test tube, a series of experiments designed to explain the mysteries of chemistry and the laws that govern it.

00:03:58 Produced by KQED San Francisco in cooperation with the California section of the American Chemical Society for the Educational Television and Radio Center.

00:04:22 And now let's go to our laboratory and meet Dr. Harry Sello.

00:04:28 Hello. The topic of this talk is combustion and combustion products.

00:04:37 Combustion, the chemist defines as a process, chemical process, in which chemical reactions occur which liberate light and heat.

00:04:50 The requirements for this chemical process are something which will burn or combust, a fuel, and air, usually.

00:05:02 We always say usually after we give a definition. That means that there must be some cases when a definition doesn't apply.

00:05:08 The chemist knows of chemical reactions in which two materials will combine, giving off a lot of light and heat, but they're not combustion.

00:05:18 Such an example is an example of iron combining with sulfur.

00:05:22 Light and heat is generated, or are generated, but this is not strictly speaking the combustion I'm referring to.

00:05:29 I'm referring to the combination of a fuel with air.

00:05:32 Here is a sample of combustion.

00:05:36 My Bunsen burner.

00:05:39 Or my match.

00:05:45 The fuel, gas, combines with air, burns at the top.

00:05:52 This is a combustion.

00:05:58 And that's what combustion looks like.

00:06:04 Now watch what happens when I pass this gauze over the flame.

00:06:11 This is a wire gauze, a screen.

00:06:17 The top of the flame is cut off.

00:06:21 Try that again.

00:06:25 The top of the flame is cut off.

00:06:28 There is no flame above the gauze, as I can illustrate by, I hope, holding this match over here.

00:06:36 This match head is not burning.

00:06:39 No flame at the top of the gauze.

00:06:43 Let's go a step further.

00:06:45 This gauze is a little hot to use at the moment. I'll just switch them and use another screen.

00:06:51 I'll slide it now just over the top of the burner.

00:06:57 Like so.

00:06:59 And lift it.

00:07:03 I actually lifted the flame from the top of the burner.

00:07:06 Let's try that again.

00:07:09 See it a little more clearly.

00:07:15 The flame actually is lifted from the top of the burner.

00:07:18 Let's flip the match in between to prove this point.

00:07:23 The right hand here, still a little warm, should be cool to be effective.

00:07:30 I'll get in here where I can see it myself.

00:07:33 Gauze on top of burner.

00:07:37 Not yet.

00:07:45 There.

00:07:47 It bounced back, but I caught it in time.

00:07:49 Note that the flame is actually being lifted off the top of the burner.

00:07:56 Let's explain what happened here.

00:08:01 When I cut the flame with the gauze, what I did was to conduct the heat of the flame away along the gauze.

00:08:12 So that above the gauze, although the gas was coming through along with air necessary to burn, it could not burn because there wasn't enough heat.

00:08:21 The heat was escaping along the gauze.

00:08:24 In the same way, when I lift the flame off, I just reverse the process.

00:08:30 The heat is escaping, cannot light the gas underneath it.

00:08:35 So, to have combustion, you need three things.

00:08:38 A fuel, air, and heat.

00:08:42 Take away any one of them, and the combustion stops.

00:08:47 We will now stop the combustion by taking away everything.

00:08:53 Let's look a little further at the sort of flames that are possible in the laboratory.

00:09:02 I have here a liquid fuel this time.

00:09:10 Pour a little bit into each beaker.

00:09:24 Combustion.

00:09:26 The fuel is burning, generating a lot of soot.

00:09:29 Quite a bit.

00:09:31 Well, anybody knows that to put out a fire, you have to throw a little water on it, so let's do that.

00:09:37 Whoops.

00:09:39 Nothing happened.

00:09:40 Well, maybe we've got something that will work better.

00:09:45 There.

00:09:46 And, let's put this one out.

00:09:53 Almost put the lecturer out too.

00:09:57 The fuel was benzene.

00:09:59 The benzene burned in the presence of air with that sooty yellow flame.

00:10:05 Now, when I threw water in the benzene, I did not put out the fire.

00:10:09 This is a significant point about this kind of fire.

00:10:12 You see, the benzene is less dense than the water.

00:10:14 The water fell to the bottom of the beaker, underneath the benzene.

00:10:18 The benzene continued to burn on top of the water, so that the water, although we know it can put out fires, is not good, not effective for putting out a benzene fire.

00:10:28 What we needed was something to mix with the benzene, which itself would not burn, that is the material we mixed in.

00:10:35 Such a material is carbon tetrachloride, present in those fire extinguishers, which we call pyrene fire extinguishers.

00:10:45 The carbon tetrachloride is not a fuel, will not burn.

00:10:48 It diluted the benzene, prevented the benzene from burning.

00:10:51 So, remember the three things, fuel, air, and heat are necessary.

00:10:56 This time, we cut out the fuel effect by throwing in carbon tetrachloride.

00:11:01 This brings us to a point about fires of such liquids as benzene.

00:11:08 It is very dangerous to throw water on such a fire.

00:11:11 You see, what you'll do is really spread the fire out, as a matter of fact.

00:11:14 The water can kick the benzene along, throw out the flaming benzene in all directions, and even worsen the fire, or gasoline, or any such material.

00:11:26 The flame was quite sooty.

00:11:28 A lot of carbon was generated.

00:11:30 That is a product of combustion.

00:11:32 Let's look at another kind of such sooty flame.

00:11:36 Here is a solid fuel this time.

00:11:45 The odor of this resembles mothballs, or mothflakes.

00:11:50 It's probably so because it is mothflakes.

00:11:54 To the chemist, this solid fuel is dephthalene.

00:12:06 Now, for this, I will need to have not a luminous flame, but a clean blue flame, which I notice now I can barely see.

00:12:17 I wonder where the yellow went.

00:12:21 There it is.

00:12:28 Open up to a little more air here.

00:12:36 I'll see if I can get this flame down on the naphthalene.

00:12:40 The naphthalene is melting now.

00:12:46 It continues to melt.

00:12:58 Soot is now being developed, and there is about the sootiest kind of a flame you can get.

00:13:06 Really thick chunks of soot.

00:13:08 Actually, it is by the burning of such material as naphthalene, types of petroleum fractions, by which soot is made commercially.

00:13:17 Commercial soot is called lamp black.

00:13:20 Lamp black, used in tires, printing inks, and dyes.

00:13:27 Actually pure carbon.

00:13:30 So, product of combustion, soot, arising from this naphthalene burning.

00:13:37 Let's look further at another product of combustion.

00:13:47 Here's our old friend, the candle again.

00:13:52 Now, we know that the candle gets its fuel from the wax, which rises up the capillary, the wick, and finally burns at the top.

00:14:02 I'll let this flame develop a little bit.

00:14:10 Now, to see this, I should more properly put a dark background behind it, so as to highlight the effect it says here.

00:14:22 Now, here's a clean beaker.

00:14:25 Looks clean.

00:14:28 All the equipment in this laboratory is clean.

00:14:32 I want that flame to just build up a little higher yet, so we make sure we see this particular product of combustion.

00:14:40 The candle is also a sooty flame.

00:14:42 You see, it has carbon in it.

00:14:43 That is why it's so luminous and yellow.

00:14:46 Combustion, but an imperfect combustion.

00:14:49 The gas burner, which has no visible flame when it's burning fuel and air in the proper proportions, is a perfect combustion, let's say.

00:14:58 Perfectly clean.

00:14:59 All the fuel is being used.

00:15:01 Now, I'll hold the beaker over the candle.

00:15:03 I think it's far enough now.

00:15:09 There.

00:15:14 There's a fog developing on the candle.

00:15:18 Not on the candle, but on the beaker.

00:15:21 Now, the fog has disappeared due to the heat.

00:15:24 That fog is water arising from the burning of the candle.

00:15:29 The water vapor condensed on the beaker made itself visible by forming a film or a fog on the glass.

00:15:37 This water is yet another product of combustion.

00:15:47 Let's go on with this product of combustion.

00:15:54 We've already mentioned that water vapor is a product of combustion.

00:15:59 Soot from a imperfect combustion is a product.

00:16:02 There are many other products, some of which we cannot illustrate by simple experiments.

00:16:08 Such products as carbon monoxide, hydrocarbons being generated from the fuel.

00:16:18 Let's see if we can illustrate yet another product of combustion.

00:16:36 I've got a little gadget in here.

00:16:39 Just a flask with a rubber stopper, two holes in the rubber stopper.

00:16:44 One side goes to a funnel and the other side to a suction bulb.

00:16:53 I'll put this out here.

00:17:02 Now, let's see, this should be under the level of the liquid and it is.

00:17:09 I'll hold the funnel over the flame.

00:17:14 There, suction on the bulb draws gases into the liquid.

00:17:19 Get it over here so it won't tip.

00:17:38 If I suck a little too hard on this bulb or a little too fast,

00:17:42 the suction itself can put out the candle flame, which will end the experiment right there.

00:17:46 Perhaps you can see the effect of the suction right on the flame.

00:17:49 It sort of jumps a little bit every time I squeeze the bulb.

00:17:52 Now, note that the formerly clear water in the flask is now turning milky.

00:18:00 There must be something coming into that water that was not present before.

00:18:05 And said something is coming from the flame of the candle.

00:18:12 Now quite milky.

00:18:15 This material in the flask is a chemical compound, a solution of a chemical compound known as calcium hydroxide,

00:18:24 more popularly lime or the solution of it, lime water.

00:18:29 Lime water has the property, or calcium hydroxide has the property,

00:18:33 that it reacts chemically very readily with carbon dioxide.

00:18:38 In the presence of carbon dioxide, calcium carbonate is formed.

00:18:43 That calcium carbonate is what makes the water milky.

00:18:47 Lime water plus carbon dioxide forms calcium carbonate.

00:18:53 Thus we have here a test for showing the existence of this product of combustion, carbon dioxide.

00:19:01 CO2 to the chemist and to anyone who has seen this written down before.

00:19:10 Carbon dioxide is, as I say, one of the products of a combustion.

00:19:15 What else is required is the fact that the fuel being used contained carbon to begin with.

00:19:21 That carbon, present in the wax of the candle, goes on to burn with air to form carbon dioxide.

00:19:28 Turns the lime water milky.

00:19:31 Here I have a beaker of carbon dioxide.

00:19:38 I put a steel beaker on the inside of some carbon dioxide.

00:19:45 The frost on the outside of the beaker is due to the fact that the carbon dioxide is cold

00:19:49 and moisture has condensed on the steel beaker.

00:19:52 Now just so that we can see what happens, let me spoon out some of this in this little beaker here.

00:20:00 That ought to be enough.

00:20:06 Switch over to a fresh batch of lime water.

00:20:10 See if we can prove that it is carbon dioxide that turns lime water milky.

00:20:20 That ought to be about enough.

00:20:24 Take this little setup and just switch right over to this flask.

00:20:29 I think I better wipe the end of this before starting because it already is a little milky.

00:20:35 We don't want any of the milkiness to come from anything but this experiment.

00:20:44 Now we'll do the same thing, only instead of using the candle, use the beaker of carbon dioxide.

00:20:55 Never let it be said that a lecture doesn't have to work for a living.

00:21:01 We'll go a little faster here since we don't have to worry about snuffing out a candle flame.

00:21:08 And now the water is turning milky.

00:21:15 Quite milky.

00:21:16 As a matter of fact, it happens a lot faster than it does with the candle

00:21:19 because this is such a concentrated source of carbon dioxide.

00:21:23 Now some of you may say, well, carbon dioxide is a gas.

00:21:25 What are you doing having it in a beaker like that, in a solid form?

00:21:29 The answer is simple.

00:21:30 It's a solid carbon dioxide, commonly known as dry ice.

00:21:34 The term dry ice, however, is not quite the right description of this.

00:21:38 It's sort of a familiar description.

00:21:40 Ice because it's cold, I suppose, and dry because it's an ice that's not formed from water.

00:21:46 Carbon dioxide is a very important commercial gas.

00:21:50 It has many uses.

00:21:51 It can be used in certain films to illustrate the properties of carbon dioxide.

00:21:57 It is also used in the carbonation of many beverages.

00:22:02 Carbon dioxide is a natural product of fermentation, for example,

00:22:06 and then will occur when a grain ferments, forming all sorts of interesting liquids.

00:22:12 Carbon dioxide can be present, or will be present, rather.

00:22:16 Also, it can be used to extinguish flames.

00:22:20 Since carbon dioxide itself will not support combustion.

00:22:24 This, then, is the other product of combustion that we have illustrated, carbon dioxide.

00:22:31 Let's look a little further into the properties of carbon dioxide.

00:22:41 Now I mentioned that the carbon dioxide in this beaker has chilled the beaker down sufficiently

00:22:45 so that there is a layer of frost on the outside of the beaker that is snow, actually.

00:22:53 However, there is also a layer of snow, I noticed, over the particles of carbon dioxide, over the chunks.

00:22:58 You see, each little chunk gets covered over with water vapor from the air.

00:23:02 So I better put this back in here.

00:23:10 This will break up the chunks and open up some fresh surfaces of the solid piece of carbon dioxide

00:23:18 so we can make sure I get enough of it here as we need it.

00:23:23 There, I think I've been sufficiently impressed, impressive here that we do a little work.

00:23:28 Now, I'll light the little candles in this trough.

00:23:39 I'll use this taper again as a way of lighting the candles.

00:24:06 This is a trough with five candles down the length of it.

00:24:17 This beaker contains nothing but carbon dioxide, nothing up my sleeves, except my arm.

00:24:25 Now let me just pour.

00:24:29 And there.

00:24:33 Without the trough being slightly inclined, the candles went out in sequence.

00:24:39 That was a pretty nice one.

00:24:40 I'd like to try that one again.

00:24:42 Probably should quit while I'm ahead here.

00:24:44 But let's see if we just can't whip through that again.

00:24:50 Use my taper for the rest of them.

00:25:13 There they go, five right in a row.

00:25:16 The bottom one is lower than the top one, not much but enough.

00:25:21 And I am pouring from an elevation here.

00:25:24 The fog that is visible is not carbon dioxide, but the water which is condensing in the area around the cold carbon dioxide.

00:25:32 But the fog indicates how the carbon dioxide is going.

00:25:36 It comes down out of the beaker, runs down the trough, and puts out the candles in sequence.

00:25:41 All of this proves simply this, that carbon dioxide is heavier than air.

00:25:45 It is more dense than air.

00:25:47 So it will always go down underneath air.

00:25:51 Well, let me take my candle here and show you further that if I have a...

00:25:58 I'll use this beaker, a little cleaner.

00:26:01 Empty beaker which I'll fill with carbon dioxide.

00:26:06 I think it's pretty full now, just about getting there.

00:26:13 You may not think it's full, but I can see that it is.

00:26:22 Beaker of carbon dioxide and still continues to put out a candle.

00:26:28 The properties illustrated here are the following.

00:26:31 Carbon dioxide is heavier than air and it will not support combustion.

00:26:36 That is, it will blanket out a flame so that the flame cannot get the air it needs and therefore will suffocate.

00:26:43 This is the reason why carbon dioxide makes such a good fire extinguishing material.

00:26:48 I would like to mention something that I neglected to mention before.

00:26:52 And that is the use of carbon tetrachloride as a fire extinguishing material.

00:26:57 It is a very good such material.

00:27:01 However, there is one precaution that must be observed.

00:27:03 And that is that when carbon tetrachloride or pyrene is sprayed on a fire,

00:27:08 it is important that whoever is doing the spraying get out of that vicinity as fast as possible.

00:27:14 Because carbon tetrachloride in the presence of a flame will break down to another gas called phosgene,

00:27:22 which is extremely highly toxic.

00:27:24 In fact, it's so toxic that it was once used as a war gas in World War I.

00:27:30 For that reason, when carbon tetrachloride is used in a fire,

00:27:33 care should be taken that you do not stay in the enclosed space very long.

00:27:38 In fact, the best way to use carbon tetrachloride is not to use it.

00:27:41 Use carbon dioxide instead.

00:27:46 Let's go on further and look at a little bit more about combustion.

00:27:51 For this purpose, I'll need a little more lime water here,

00:27:54 which I should have kept stoppered, I see.

00:27:57 I'll explain here.

00:27:58 And my screen.

00:28:05 The lime water you see being open was exposed to air.

00:28:08 There is a tiny amount of carbon dioxide in our normal atmosphere.

00:28:12 Already the top of this lime water shows tiny traces of a slight, slight milkiness.

00:28:19 Not much, but some, showing that carbon dioxide is present in the atmosphere.

00:28:24 And another proof of the fact that carbon dioxide is around.

00:28:28 I'll pour a little bit of this into this beaker.

00:28:36 Now, since I'm through using it, I'll cap it.

00:28:55 Ah.

00:29:08 The water was clear to begin with.

00:29:10 By blowing my hot little breath through it, the water, the lime water that is, has turned milky.

00:29:24 This shows that there is carbon dioxide present in my breath.

00:29:29 Well, let's sort of look back along this little fact and track it back your ways.

00:29:34 Where did the carbon dioxide come from?

00:29:37 Well, you and I are little combustion engines of a sort.

00:29:42 A combustion engine, or a combustion you know, liberates a lot of light and heat.

00:29:47 Well, we too liberate heat.

00:29:50 Not so much light, although I've seen some people who have a glow on.

00:29:54 However, we do liberate heat.

00:29:56 That's how we maintain our body temperature.

00:29:59 We have a slow combustion going in our bodies at all times.

00:30:04 We take in oxygen, we have the fuel present inside of us from the food,

00:30:09 and the body temperature generates the heat necessary for combustion.

00:30:13 Well, let's summarize.

00:30:17 We have illustrated the process of combustion.

00:30:23 Combustion means that a fuel can combine with air in a chemical reaction to produce light and heat.

00:30:33 This we illustrated in several ways.

00:30:35 A burner flame, a candle flame, and the burning benzene.

00:30:41 We also illustrated that heat is necessary for the combustion.

00:30:45 In fact, there were three things necessary, fuel, air, and heat.

00:30:50 We illustrated that heat was necessary because when we hold a wire gauze over a burner flame,

00:30:56 the wire gauze conducts away the heat,

00:30:59 so the gas burning below the gauze gets through the gauze,

00:31:03 but on top does not burn because the gauze conducts away the heat.

00:31:08 In fact, when you throw water on a fire,

00:31:10 you probably stop a fire just as much by cooling down the fuel,

00:31:13 that is, cutting down the heat, as well as smothering the fire itself.

00:31:18 We then went to illustrate products of combustion.

00:31:21 They were soot or carbon, carbon dioxide, water vapor.

00:31:28 Other products which were not illustrated but which are present are carbon monoxide and various hydrocarbon gases.

00:31:35 Finally, we showed the properties of carbon dioxide.

00:31:38 That is, it is heavier than air, it can be obtained as a solid at very low temperatures,

00:31:43 and it will not support combustion.

00:31:46 Thank you.

00:32:08 ♪♪

00:32:35 This is National Educational Television.