464 THE POPULAR SCIENCE MONTHLY. 



nized compounds are formed by the union together of two or more 

 supposed elements ; and no revelations concerning the nature of the 

 latter can well disturb that established knowledge. However we may- 

 speculate, the experimentally-ascertained facts will remain unaltered. 

 They may receive slightly diiferent theoretical interpretations, with- 

 out having their practical bearings changed in the least degree. 



The prevalent view of the subject, that the elements are element- 

 ary, is held by philosophical chemists in a purely provisional way. 

 We need a convenient working hypothesis, and these sixty-three sub- 

 stances are elements for aught we absolutely know to the contrary. 

 As far as we are at present experimentally concerned, then, we call 

 them elements, bearing always in mind the possibility that they may 

 be compounds. They have never been decomposed ; we have no 

 means adequate to their analysis ; not one of them can be obtained 

 from materials in which it does not already exist. But all this evi- 

 dence is only negative. How do we know but that some future dis- 

 covery may render possible the decomposition of these supposed ele- 

 ments ? Shall we assert positively that we have reached the ultimate 

 analysis, and may never hope to go any farther ? Obviously, so defi- 

 nite a statement would be unjustifiable, and no sane chemist would 

 venture to make it. The uncertainty of the subject may well be illus- 

 trated by a reference to chemical history. At the beginning of the 

 present century the alkalies and alkaline earths were thoxight to be 

 elements. They were not decomposable by any m^eans then known, 

 so that the supposition was perfectly fair. A very few years passed 

 away, the galvanic battery was brought into use, and presently it was 

 found that each of these bodies was a compound, containing a metal 

 united with oxygen. Perhaps a similar advance in our knowledge 

 may demonstrate the possibility of decomposing many of the sub- 

 stances now regarded as elementary. Such a discovery might work 

 in either one of three ways. It might largely increase the number of 

 supposed elements, by dividing each one into two or more new bodies. 

 It might reduce the number by proving that our elements were formed 

 by the union, in various proportions, of only a very few simpler sub- 

 stances, Or it might demonstrate the unity of matter, just as recent 

 science has demonstrated the unity of force, and give us only one true 

 element underlying all material forms. Such a culmination of our 

 knowledge would be grand, indeed ! 



The evidence, then, upon which we assert the elementary nature 

 of the fifty metals and thirteen non-metals, is very incomplete. On 

 this side of the question there is really no other important testimony, 

 save that just cited. Arguing from our present inability to decompose 

 certain bodies, we assume for convenience that they are indecom- 

 ' posable. Now^ let us see what there is in favor of the opposite view. 



One of the first things learned by the student in chemistry is, that 

 the so-called elements are readily classifiable into a few natural groups. 



