麻豆传媒

READERS CONTINUE to send in stories of the carefree nature of school science experiments in the less safety-conscious days of yore. For example, as we pointed out on 25 March, the hazards of mercury were unknown, or at least ignored, in those days. Richard Lawson and Ian Field both remember an experiment demonstrating the emission and absorption of light, in which the darkened laboratory was illuminated by a mercury vapour lamp. A large crucible of mercury was then heated over a Bunsen burner, and the class watched shadowy patterns on the wall formed by the rising mercury 鈥渟team鈥� as it slowly filled the room (and the pupils鈥� lungs).

Field also recalls an experiment to show that hydrogen sulphide causes a loss of the sense of smell. A Kipp鈥檚 apparatus was brought into the laboratory and turned on to produce the gas. The pupils 鈥渧ery rapidly鈥� agreed that they could smell it. Field was then the lucky volunteer to leave the class for a few minutes while the apparatus was left on. 鈥淲hen I returned the smell was appalling, but the rest of the class had reached a state of blissful ignorance.鈥�

L. C. Walters, on the other hand, points out that 鈥渟ense of smell was a primary tool of chemical analysis鈥� in the old school science labs. Pupils regularly took 鈥済ood sniffs鈥� at test tubes or bottles emitting chlorine, bromine, nitrogen dioxide, carbon disulphide, sulphur dioxide, hydrogen chloride and so on.

Small wonder that chemistry was known as 鈥渟tinks鈥� a point underlined by Mart Martin, who remembers that if a dozen Bunsen burners were in use on a windy day, doors and windows were closed to avoid the risk of one blowing out unobserved; there were, of course, no fume cupboards.

Out of school, Martin also recalls preferring asbestos as a DIY material because it was easy to saw, drill and file. As a fit and active 77-year-old who survived these and other dangers, he wonders 鈥渨hether the fervour with which we are now encouraged to cosset ourselves is not perhaps just a mite OTT鈥�. This view was echoed by several other correspondents.

MEANWHILE, Alan Calverd writes: 鈥淚 recall a class of thirty boys holding hands in a circle that was completed by an induction coil. We were still giggling with embarrassment at the cissy handholding when we were treated to a sharp 25-kilovolt pulse 鈥� Several of the survivors have achieved eminence in physics, electrical engineering and folk dancing.鈥�

One can hardly imagine teachers these days treating their pupils like that. But David Stevenson defends the teachers of old against the accusation that they were indifferent to the safety of their charges. His teacher, after all, made the pupils put on gas masks while he walked round the lab with a boiling tube emitting chlorine.

But even this teacher, like many others, happily allowed the pupils to suck pipettes by mouth, and Stevenson recalls getting a mouthful of oxalic acid during a practical exam 鈥� which, he says, was spat out 鈥渨ith haste鈥�.

IT WASN鈥橳 only the teachers whose attitudes were different from those held today. The books were in the same vein. For example, the science section of Peter Bartley鈥檚 copy of The Treasure House Children鈥檚 Encyclopaedia of 1920 suggests children perform this charming little experiment to learn about combining iron and sulphur:

鈥淗eat a solid rod of iron in the fire till it is nearly white-hot, and then touch it with a stick of brimstone. The fused iron sulphide drops down, and the iron rod apparently melts away.鈥�

One wonders at what age children were expected to perform such an experiment 鈥� or, even worse, this one, discovered by Thomas Ashley in a book called Junior Science Projects, published as recently as 1967 by Arco Publishing, New York:

鈥淪uspended animation. Quick-freezing has been one method proposed to keep men alive on long trips through space. You can demonstrate the harmlessness of quick-freezing on body tissues with liquid nitrogen and a small goldfish. Catch the fish in a small net and then dip the net and the fish into the liquid for no more than 15 seconds. If the fish gets too cold, it will be difficult to thaw it evenly enough to revive it. In this short time the fish is thoroughly frozen and will be completely rigid. (Don鈥檛 drop him or he鈥檒l shatter.) To revive the fish, just put him back into the fishbowl where he鈥檒l thaw immediately and swim away, none the worse for wear.鈥�

It seems hard to believe such an experiment would work. But if it did, how many enterprising junior scientists went on to attempt it on the cat?

Or, worse still: 鈥淚 say, let鈥檚 try it on Jenkins Minor!鈥�

BUT NOTHING demonstrates how attitudes have changed as much as the following, found by Eugene Doherty in The Boy Electrician by J. W Sims (7th Edition, Geo. Harrap & Co., 1955).

鈥淴-rays. Most young experimenters are unaware what a wonderful and interesting field is open to the possessor of a small X-ray tube. Small X-ray tubes which will operate satisfactorily on an inch and one-half spark-coil may be obtained from several electrical supply houses. They usually cost about twenty shillings or so. With such a tube and a fluoroscope it is possible to see the bones in the human hand, the contents of a small purse, etc.鈥�

Hours of fun for all the family! Except, Doherty tells us, the original edition of this book was written in 1920. By 1955 people had become a little more fuddy-duddy about things like X-rays, so the edition of that year carries a warning: 鈥淚f the skin be exposed directly to X-rays for only a few minutes an irritating and even dangerous inflammation may result. It is therefore necessary to be extremely careful not to overexpose any part of the body.鈥�

Which makes everything alright, doesn鈥檛 it?

FINALLY, a 麻豆传媒 contributor who shall be nameless remembers being on the other side of the fence in the stinks lab.

鈥渓 taught science for one term immediately after university. I can鈥檛 for the life of me remember why I showed the class an experiment which involved mixing potassium permanganate with hydrogen peroxide, in some kind of sealed container. But I do vividly remember how it erupted in a mushroom cloud of purple foam. All I could think of saying was a stern 鈥楾here, that shows you that when I say 鈥渟tand back鈥�, I really do mean 鈥渟tand back鈥�.鈥� I also vividly remember one of the purple-stained kids asking, 鈥楾hen why are you covered with the stuff too, sir?鈥濃��

THANKS TO everyone mentioned, and to the many more who wrote to Feedback with memories of more casual times. They were all a delight to read, but space forbade printing any more. Though this theme is a rich one, we shall be leaving it for now.