MAY, 1955
the factitious normality system be completely scrapped. Problems in volumetric analysis can be solved more readily by using a millimole analysis. The millimole method has in its favor the emphasis on the equation of the reaction actually taking place in the titrationvessel. To me this makes good teaching sense.
To the Editor: Dr. Meldrum's paper on the teaching of equivalent weights (THIS JOURNAL, 32, 48 (1955)) is testimonial to t,he difficulty of presenting this topic to students. Many practicing teachers may have murmured "How true!" when they read the conclusion that "teaching of equivalents is a situation which is, for the most part, vague and baffling to the student." Has not the time come t o bring up for debate the question of the advisability of teaching the equivalent concept? I realize that anyone who would suggest the possibility that t,he equivalent concept is not indispensable is certainly spitting into a very high wind. Students do seem to gain without too much difficulty a working concept of such concrete material as atoms, molecules, electrons, and molecular weights. But the nebulous equivalent never seems quite to gel. For what it is worth, may I venture to suggest that
To the Editor: On page 668 of the December, 1954, issue of THIS JOURNAL, A. Viswanathan and S. Azmatullah mention the behavior of soap bubbles blown by a person who has inhaled hydrogen. They mention the danger of breathing hydrogen containing poisonous impurities, but they neglect the more serious danger of explosion. Several people have been killed while demonstrating the effectof hydrogen on the pitch of spoken words. People who wish to blow light bubbles should stick to helium. Otherwise they are in danger from any accumulation of static electricity-especiauy during the winter conditions the authors (in Madras) do not need t,o worry about. RICHARD M. NOYES COLUMBIA UNIVE~ITY NEW YORK, N. Y.
