WRITINGS OF JAME3 SMITHSON. 37 



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

 figure : 



fl rrolor, J Sulphur 



Compound sulphuret 1 $ lead 



of lead, antimony, = j f sulphuret of f sulphur, 



and copper - * antimony ={| antimony. 



( * fahlertz = j f su l p huret of ( 1 sulphur/ 

 [ copper \ | copper. 



Its ultimate elements are therefore, 



Sulphur 20 . . . = f 



Lead 41f . . . = f 



Antimony 25 . . . = H 



Copper 13 J . . . = -gV 



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 are 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. 



