WRITINGS OP JAMES SMITHSON. 87 



chemical analysis has yet been able to go, by the following 

 figure : 



Compound Bulphuret 

 of lead, antimony, = 

 and copper 



}g.Ie„={|-X- 



■ f eulphuret of f ^ sulphur. 



1 foiiio t J antimony \ 4 antimony. 



L i laniertz _ ^ ^ gulphuret of _ ? } sulphur. 

 [_ copper \ I copper. 



Its ultimate elements are therefore, 



Sulphur - - 20 . . . = |2 



Lead - - - 41f . . . = | a 



Antimony - - 25 . . . = ^-§ 



Copper - - 13J . . . == /o 



and it is not a little remarkable, that here, as was the case 

 •with the calamine,* they are sexagesimal fractions of it. 



When in a former paper I offered a system on the pro- 

 portions of the elements of compounds, I supported it by 

 the results of my own experiments, which might be sup- 

 posed influenced, even unconsciously to myself, by a favour- 

 ite hypothesis, and I made the application of it principally 

 to a substance whose nature was not very clear. But the 

 present case is not liable to these objections : here no fond- 

 ness to the theory can be suspected of having led astray, 

 nor did even the experiments as they came from their 

 author's hands, bear an appearance in the least favourable 

 to it, and yet when properly considered, they are found to 

 accord no less remarkably with its principles. 



It is evident that there must be a precise quantity in 

 which the elements of compounds arc united together in 

 them, otherwise a matter, which was not a simple one, 

 would be liable, in its several masses, to vary from itself, 

 according as one or other of its ingredients chanced to pre- 

 dominate ; but chemical experiments are unavoidably at- 

 tended with too many sources of fallacy for this precise 

 quantity to be discovered by them ; it is therefore to theory 



* Phil. Trans. 1803, p. 12. 



