SBLPHUREf OF LEAD, ANTIMONY, AND COPPER. 333 



phuret, as that which had been laid before the Society is 

 Tery materially inaccurate and imperfect. 



We have no real knowledge of the nature of a com- To know the 

 pound substance, till we are acquainted with its proximate "^^"'"'^ °^/ 



' ^ ^ compound wc 



elements, or those matters by the direct or immediate union must find its 

 ©f which it is produced ; for these only are its true elements. P™'^''"^^^^ 

 Thus, though we know that vegetable acids consist of 

 oxigen, hidrogen, and carbon, we are not really acquaint- 

 ed 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 example, did we only know that a crystal of it 

 consisted of iron, sulphur, oxigen, and hidrogen; or of 

 carbonate of lime, if only that it was a compound of lime, 

 carbon or diamond, and oxigen. In fact, totally dis- 

 similar substances may have the same ultimate ele- 

 ments, and even probably in precisely the same proportions ; 

 nitrate of ammonia, and hydrate of ammonia, or crystals 

 of caustic volatile alkali*, both ultimately consist of 

 oxigen, hydrogen, and azote. 



It is not probable, that the present ore is a direct qua- The ore pro- 

 druple combination of the three metals and sulphur, and that ^^ three'suU*'* 

 these, in their simple states, are its immediate component pharets. 

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

 the three sulphurets of these metals. 



On tills 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, lOgrssuIphnret 

 to produce 12*5 grains of sulphate of lead. Hence the°2 5Llphater' 

 60-1 grains of sulphate of lead, which Mr. Hatchett obtained, 

 correspond to 48-08 grains of sulphuret of lead. 



I have found 10 grains of sulphuret of antimony to af- iCgrs sulphuret 

 ford 11 grains of precipitate from muriatic acid by water. gf/s^\'^h°"J. ^^ 

 Hence 31-5 grains of this precipitate are equal to 28-64 

 grains of sulphuret of antimony. 



The want of sulphuret of copper has prevented my de- 

 termining the relation between it and black oxide of copper, 



* Fourcroy, Syst.. da Con, Chem, 1. 1, p. Ixxxviii. Transl. 1, 100. 



but 



