WRITINGS OF JAMES SMITHSON. 27 



to arid vitriol of zinc, fractions of the compound of very 

 low denominators. Possibly in few cases exceeding five. 



The success which has appeared to attend some attempts 

 to apply this theory, and amongst others, to the composi- 

 tions of some of the substances above analysed, and espe- 

 cially to the calamine from Bleyberg, induces me to venture 

 to dwell here a little on this subject, and state the composi- 

 tion of this calamine which results from the system, as, 

 besides contributing perhaps to throw some light on the 

 true nature of this ore, it may be the means likewise of 

 presenting the theory under circumstances of agreement 

 with experiment, which from the surprising degree of near- 

 ness, and the trying complexity of the case, may seem to 

 entitle it to some attention. 



From this calamine, containing, according to the results 

 of the experiments on the Mendip Hill kind, too small a 

 quantity of carbonic acid to saturate the whole of the calx 

 of zinc in it, and from its containing much too large a por- 

 tion of water to be in it in the state of mere moisture or 

 dampness, it seems to consist of two matters ; carbonate of 

 zinc, and a peculiar compound of zinc and water, which 

 may be named hydrate of zinc. 



By the results of the analysis of the Mendip Hill cala- 

 mine, corrected by the theory, carbonate of zinc appears to 

 consist of 



Carbonic acid - J 



Calx of zinc 



Deducting from the calx of zinc in the Bleyberg cala- 

 mine, that portion which corresponds, on these principles, 

 to its yield of carbonic acid, the remaining quantity of calx 

 of zinc and water are in such proportions as to lead, from 

 the theory, to consider hydrate of zinc as composed of 



Calx of zinc . - f 



Water, or rather ice 



And, from these results, corrected by the theory, I consider 

 Bleyberg calamine as consisting of 



Carbonate of zinc - - |- 



Hydrate of zinc ... 



