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fashion of Professor Henry E. Armstrong and the late Dr. R. W. Raymond who followed the same practice during his whole life. Only untiring industry could have made such a habit possible. He was industrious and has left a record of which his friends may well feel proud.
"THE LAW OF AVOGADRO" T o the Editor: Let me call your attention t o an error, or a t least an ambiguity, in the article on "The Law of Avogadro" which appeared in the November number of the JOURNAL. The author of this article has attempted a so-called "deductive proof" of Avogadro's Hypothesis. It is thoroughly familiar t o all how this principle arises out of Gay-Lussac's Law of Combining Volumes and (as the author correctly points out) from the Law of Combining Weights. In the traditional development of this topic we are led to see that as a result of these two principles the number of molecules in equal volumes of different gases must be either equal or simple multiples of each other. Avogadro's Hypothesis, of course, merely fixes the choice on the first and simplest alternative. I n theauthor's "deductiveproof" theequation, VJV2 = nn/%lXN1/N2is used, where V,/V2, the ratio of combining volumes, and NI/N2, the ratio of total molecules reacting, are both whole numbers, whence, the author suggests, nz cannot be not equal t o n, (themumbers of molecules in equal volumes). The mathematical fallacy of this is apparent, however, for to fulfil the conditions i t is only required that nz = bnl, where b is any whole number, not necessarily 1. And this gets us nowhere with respect t o fundamental assumption of Avogadro's Hypothesis. Nonnrs W. RAKESTRAW OBERLINCOLLEGE, OBERLIN, OHIO
CAN YOU HELP US?
W e publish the following letter from Dr. Silverman in the ho$e that some of our readers may be able to supply the desired information. At the Los Angeles session of the Division of Chemical Education someone quoted Le Chatelier as having said, "Students are not re-
