-^ CHEMICAL ANALYSIS OF SOME CALAMINES. 



of zinc, excepting an inappreciable quantity of vitriol of lime in 

 capillary cryftals, due, without doubt, to a flight and accidental 

 admixture of iorne portion of the calcareous fragments on which 

 this calamine had been depofited. Pure martial prulTiate of 

 tartar, threw down a white precipitate from the folution of this 

 fait. 



In another experiment, 20.0 grs. of this calamine afforded 

 28.7 grs. of arid vitriol of zinc. 



d. 10 grs. of this calamine were diffolved in pure marine 

 acid, with heat. On cooling, fmall capillary cryftals of muriate 

 of lead formed in the folution. This Iblution was precipitated 

 by carbonate of foda, and the filtered liquor let exhale flowly in 

 the air ; but it furniflied only cryftals of muriate of foda. 



e. 10 grs. diflblved in acetous acid without leaving any refi- 

 duum. By gentle evaporation, 20.3 grs. = 2.03. of acetite of 

 zinc, in the ufiial hexagonal plates, were obtained. Thefe cryf- 

 tals were permanent in the air, and no other kind of fait could 

 be perceived amongft them. 



Neither folution of vitriolated tartar, nor vitriolic acid, occa- 

 lioned the flighteft turbidnefs in the folution of thefe cryftals, 

 either immediately or on ftanding ; a proof that the quantity of 

 lime and lead in this folution, if any, was exceffively minute. 



/. A bit of this calamine, weighing 20.6 grs. being made red 

 hot in a covered tobacco-pipe, became very brittle, dividing on 

 the flighteft touch into prifnis, like thofe of ftarch, and loft 5.9 

 grs. of its weight = 0.286. After this, if diffolved flowly and 

 difficultly in vitriolic acid, without any effervefcence. 

 The ca'amine According to thefe experiments, this calamine confifts of, 

 contained oxide Calx of zinc - - - 0.714 



of zinc, car- ^ , . ■ , 



bonic acid, and Carbonic acid - - - 0. 1 35 



water. Water - - - - - 0.151 



1 .000. 

 The carbonates of lime and lead in it are more accidental 

 admixtures, and in too fmall quantity to deferve notice. 



Calamine from Somerfetjhire. 

 Somerf^tftiire a. This calamine came from Mendip Hills in Somerfetfliire. 



It had a niammillated form ; was of a denfe cryftalline tex- 

 ture ; femitranfparent at its edges, and in its fmall fragments ; 

 and upon the wliole very fimilar, in its general appearance, to 

 calcedony. 



It 



calamine. 



^fll 



