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SCIENCE. 



[N. S. Vol XII. No. 309. 



and equations worked out along algebraic 

 lines. It was, doubtless, the presence of these 

 mathematical equations all through his vol- 

 umes which deterred many chemists from 

 a full and patient examination of them 

 for the kernel of truth which they might 

 contain. The average experimental chem- 

 ist is not much attracted by abstruse math- 

 ematical speculations. 



Later chemists commenting upon his 

 work have made some mention of the 

 mathematical regularities observed by him 

 and this led me to think that perhaps 

 Eichter might have caught some glimpse 

 of the periodic law before the conception 

 of the atom and the atomic theory had 

 entered into chemistry. To investigate 

 this question it was necessary to examine 

 Eichter's writings and I was fortunate 

 enough to secure the use of a copy of his 

 Stochyometrie through the courtesy of the 

 librarian of the American Academy of Arts 

 and Sciences. 



It is of interest, first, to see how near an 

 approach Richter made to the conception 

 of atoms. In the preface to Volume I. the 

 question of solution is discussed and the 

 statement is made that " the chemist can- 

 not boast of being able in any manner to 

 divide a body up into the smallest parts 

 because matter can be thought of as in- 

 finitely divisible." From many passages 

 one may judge, however, that he held to 

 the corpasclar view of matter, namely that 

 it was composed of certain very small, dis- 

 crete particles, which were, however, con- 

 ceivably further divisible. Thus in giving 

 the various definitions of elements he says 

 that to one chemist the word meant the 

 simplest indestructible substance, the subt- 

 lest material which the creator had created 

 for the formation of all other bodies; to 

 another it meant such materials as could not 

 be decomposed into dissimilar particles and 

 in which no component particles could be 

 recognized. For himself he prefers to di- 



vorce the word from all connection with 

 primal matter, or Urstoffe, and to make use 

 of it simply as a part of the chemical tech- 

 nology, attaching to it the meaning of a 

 body undecomposable by any means known 

 to the chemist. Chemistrj' as an art, ac- 

 cording to Richter, consisted in the ability 

 to separate elements from one another and 

 to bring them together as constituents of 

 a new body. Chemistry as a science was 

 something greater, including its theories 

 and fandamental axioms. A chemical ele- 

 ment, he says, is one which, without being 

 decomposed into unlike parts, can by mix- 

 ing with other kinds of matter cloak their 

 peculiar characteristics and bring about 

 others. It is elementum immediatum when it 

 cannot be decomposed into unlike parts ; 

 mediatwn when it can be thus decomposed 

 (p. 5 seq.). 



Thus, as Richter adds in a footnote, 

 vitriolic acid is an elementum immediatum, 

 since no one has been able to decompose it 

 into unlike parts, but sulphur is an elemen- 

 tum mediatum, since any one knows that it 

 can be decomposed into vitriolic acid and 

 phlogiston and reformed from these two. 

 This is of interest as showing the degree of 

 knowledge on which he based his reasoning. 

 His corpuscles are called ' Theilganzen,' 

 and in these the force of affinity resides. 

 Thus he states, " to each infinitely small 

 particle of the mass of an element there be- 

 longs an infinitely small portion of the 

 chemically-attracting force of alfinity " (p. 

 123). 



The part of Richter's work which appears 

 to refer most nearly to the periodic system is 

 found in his second volume on page vi of the 

 preface. He refers to the fact that the sup- 

 position had already been made in a paper 

 on the ' N'ewer Objects of Chemistry, espe- 

 cially the recently discovered half-metal 

 Uranium,' that the affinities of many chem- 

 ical elements towards any single one might 

 be in a definite progression. This sup- 



