82 ON THE SIGNIFICATION OF CHEMICAL TERMS. 



speaking of the number and nature of elements, he says, 

 **.| shall therefore only ad^ oi^ this subject, that, if by the 

 term elements v/a mean to express those bimple and indivisi- 

 ble atoms of which matter is composed, it is extremely 

 probable we know nothing ut all about them.'* Chaptal 

 employs about -20 pages on affinity, two on the affinity of 

 agj^regation, and the rest on the affinity of composition. In 

 ■ the third edition of your First Principles of Chemistry, I 

 observe 10 pages on affinity. Bertliollet has written a small 

 volume on the subject. Fourcroy, Thomson, Murray, and 

 ^ Henrj', have all expanded their views on this subject pretty 

 extensively. From these observations it should seem, that the 

 article affinity in systems of chemistry lias been of growing 

 importance since the time of Lavoisier's publication. This 

 may certainly be right; but as the subject is acknowledged 

 to be one of the most difficult in the science, it is highly 

 necessary, that authors should treat it with all the perspi- 

 cuity of which it is capable; the terms used should be clear 

 and well defined; metaphorical exprestsious should be 

 avoided; and ambiguities" should be guarded against with 

 all possible care. 



Chaptal. Chaptal has been very sparing in the use of the term 



/>rtr/i'c/e when treating of affinity (I refer to your translation, 

 2d ed.) ; he only mentions it three times, twice unqualified, 

 and once along with the epithet elementary \ he seems to 



Integrant part, use integrant part, w^iere others vvould use particle, and he 

 defines it thus: "two drops of water, which unite logelhet 

 into one, form an aggregate, of which each drop is known 

 by the name of an integrant part." 



l;iichoUon's On the subject of affinity I observe you use the term 



First Princi- particles frequently, but only once in the singular number. 

 jVo definition of it is ever given; but the last time it occurs 

 is fn a very judicious con/:luding remark, which I do not 

 remember to have seen in any subsequent writer; namely, 

 *' it seems reasonable to infer, that two compounded parti- 

 cles coming together by attraction, undisturbed by any 

 otlici'-cAu^^e, should dispose themselves so as to apply such 

 sidts of each together, as ate occupied by principles the 

 niost attractive of each other.'* In another jiart of the 

 -chapter you observe, that ** the minutest parts, into which 



pies 



