CHEMICAL ANALYSIS OF SOME CALAMINES. 77 



It was tinged, exteriorly, brown ; but its interior colour was 

 a greeniHi yellow. 



It had confiderabie hardncfs ; it admitted however of being Charaaers. 

 fcraped by a knife to a white powder. 



56.8 grs. ofitdifplaced 13.1 grs. of waier, at a temperature 

 of 6oo Fahrenheit. Hence h^ denfity = 4.336, 



b. Expofed to the blowpipe, it became opaque, more yellow, Blowpipe aftays, 

 and friable; fpread flowers on the coal, and confequently vola- 

 tilized, but not with the rapidity of the foregoing kind from 



Bleyberg . 



It diflblved in borax and raicrocofmic fait, with efFervefcence, 

 yielding colourlefs glafles. Carbonate of foda had no aftion 

 on it. 



c. It diflblved in vitriolic acid with a brifli efl'ervefcence ; Solution. 

 and 67.9 grs. of it emitted 24..5 grs. =0.360, of carbonic acid. 



This folution was colourlefs ; and no refiduum was left. By 

 evaporation, it afforded only vitriol of zinc, in pure limpid 

 cryftals. 



d. 23.0 grs. in fmall bits, made red hot in a covered tobaccfl- 

 pipe, loft 8.1 grs, = 0.352. It then diflblved flowly and diffi- 

 cultly in vitriolic acid, without any emiflion of carbonic acid ; 

 and, on gently exhaling the folution, and heating the fait ob- 

 tained, till the expulfion of all fuperabundant vitriolic acid and 

 all water, 29.8 grs. of arid vitriol of zinc were obtained. This 

 dry fait was wholly foluble again in water ; and folution of pure 

 martial pruflTiate of foda occafioned a white precipitate in it. 



This calamine hence confiffs of. Component 



Carbonic acid .. - - 0.352 P^'^'^' Carbonic 



Calx of zinc - - - . 0648^ ^St^"^''^ 



I. 000, 



Calamine from Derhyjhire. 



a. This calamine coafifted of a number of fmall cryftals, Derby/hire ca- 

 about the fize of tobacco-feeds, of a pale yellow colour, which '^"^'"^' 

 appeared from the fiiape of the mafs of them, to have been 

 depofited on the furface of cryfials of carbonate of lime, of 

 the form of Fig. 28. Plate IV. of the Crifiallographie of Rom€ 

 de L'Ifle. 



The fmallnefs of thefe calamine cryftals, and a want of External cha- 

 lliarpnefs rendered it impoflible to determine their form with "'^s'^s, &c. 



certainty : 



