C 55 3 
HI. On the Composition of the Compound Sulphuret from Hud 
Boys , and an Account of its Crystals . By James Smithson, 
Esq. F. B. S. 
Read January 28, 1808. 
It is but very lately that I have seen the Philosophical Trans- 
actions for 1804, and become acquainted with the two papers 
on the compound sulphuret of lead, antimony, and copper 
contained in the first part of it, which circumstance 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 giv- 
ing 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 elements, 
or those matters by whose direct or immediate union it is pro- 
duced ; 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 compo- 
sition, 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 acquaint- 
ance with sulphate of iron ; for example, did we only know 
that a crystal of it consisted of iron, sulphur, oxygene, and 
