WRITINGS OF JAMES SMITHSON. , 35 



has prevented my offering sooner a few observations on Mr. 

 HATCHETT'S experiments, which I deem essential towards 

 this substance being rightly considered, and indeed the 

 principles of which extend to other chemical compounds ; 

 and also giving an account of the form of this compound 

 sulphuret, as that which has been laid before the Society is 

 very materially inaccurate and imperfect. 



We have no real knowledge of the nature of a compound 

 substance till we are acquainted with its proximate ele- 

 ments, or those matters by whose direct or immediate union 

 it is produced ; for these only are its true elements. Thus, 

 though we know that vegetable acids consist of oxygene, 

 hydrogene, and carbon, we are not really acquainted with 

 their composition, because these are not their proximate, 

 that is, are not their elements, but are the elements of their 

 elements, or the elements of these. It is evident what 

 would be our acquaintance with sulphate of iron ; for ex- 

 ample, did we only know that a crystal of it consisted of 

 iron, sulphur, oxygene, and hydrogene ; or of carbonate of 

 lime, if only that it was a compound of lime, carbon or 

 diamond, and oxygene. In fact, totally dissimilar sub- 

 stances may have the same ultimate elements, and even pro- 

 bably in precisely the same proportions ; nitrate of ammo- 

 nia, and hydrate of ammonia, or crystals of caustic volatile 

 alkali,* both ultimately consist of oxygene, hydrogene, and 

 azote. 



It is not probable that the present ore is a direct quad- 

 ruple combination of the three metals and sulphur, that 

 these, in their simple states, are its immediate component 

 parts; it is much more credible that it is a combination of 

 the three sulphurets of these metals. 



On this presumption I have made experiments to deter- 

 mine the respective proportions of these sulphurets in it. 



I have found 10 grains of galena, or sulphuret of lead, to 

 produce 12.5 grains of sulphate of lead. Hence the 60.1 



* FOURCROY, Syst. des Con. Chem. t. I. p. 88. 



