262
Ingold) and "benzene bond" (G. Wheland) are worthy of more attention and consideration.
To the Editor: The nation-wide furor over the "torch" sweaters is reminiscent of a, similar situation whose abatement illustrated the effectivenessof methodical research. During the Victorian era many of the poorer Irish wore night clothing made of Canton flannel. As the cottages and many of the houses were heated by open fireplaces, many serious accidents and even fatalities resulted because of the ready flammability of the fleecy material. Conditions became so bad that the authorities threatened to ban the sale of this goods unless the manufacturers found a way to flame-proof it. The problem was brought to the noted chemist W. H. Perkin (1838-1907). In due time he discovered a simple solution to the problem, namely treatment with stannic chloride. When Perkin was asked how he happened to come upon this rather odd result, he smiled and said: "It was really very simple. You know that I have a large laborat,ory and it is well stocked with a large variety of chemicals, which are arranged on the shelves in alphabetical order. I began with 'A' and found what I was seeking in IS.' ' I If Perkin had been a German the story would be even more interesting; he would then have found it in "Z,"
JOURNAL OF CHEMICAL EDUCATION
since stannic chloride in German is Zinn Chlorid.
To the Editor: The note by Professor H. B. Williams on "Elementary physical chemistry and mathematics" in the February issue deserves a commentary and some support. I have experienced the same situation in physics classes, but the ideas here are not quite as illusive as those in physical chemistry. In thermodynamics the situation is truly appalling. The student often does not know whether he can integrate, or whether he ought to, or whether he can't. I t is like pondering the verb in German: the reaction may take place; the reaction should take place; the reaction must take place; and so on. I once fell heir to a class in physical chemistry (during the War) and the mathematical competence was frightful. The answer lies here: mathematics teachers should constantly ask: "What does this mean?" If students saw the physical meaning of what they are doing mathematically in each step of the analysis the process would possess some sense. As it now stands the student can manipulate if it is set up for him in standard form, but if he has to think he is licked!
