22 WRITINGS OF JAMES SMITHSON. 



and difficultly in vitriolic acid, without any emission of car- 

 bonic acid ; and, on gently exhaling the solution, and heat- 

 ing the salt obtained, till the expulsion of all superabundant 

 vitriolic acid and all water, 29.8 gra. of arid vitriol of zinc 

 were obtained. This dry salt was wholly soluble again in 

 water; and solution of pure martial prussiate of soda oc- 

 casioned a white precipitate in it. 

 This calamine hence consists of 



Carbonic acid - - - 0.352 



Calx of zinc - - - 0.648 



1.000. 

 Calamine from Derbyshire. 



a. This calamine consisted of a number of small crystals, 

 about the size of tobacco-seeds, of a pale yellow colour, 

 which appeared, from the shape of the mass of them, to 

 have been deposited on the surface of crystals of carbonate 

 of lime, of the form of Fig. 28, Plate IV. of the CristaUo- 

 graphie of Home de L'Isle. 



The smallness of these calamine crystals, and a want of 

 sharpness, rendered it impossible to determine their form 

 with certainty ; they were evidently, however, rhomboids, 

 whose faces were very nearly, if not quite, rectangular, and 

 which were incomplete along their six intermediate edges, 

 apparently like Fig. 78, Plate IV. of Home de L'Isle. 



22.1 grs. of these crystals, at a heat of 57° Faurenheit, 

 displaced 5.1 grs. of water, which gives their density 3:z; 

 4.333. 



Heat did not excite any electricity in these crystals. 



b. Before the blowpipe, they grew more yellow and 

 opaque, and spread flowers on the coal. They dissolved 

 wholly in borax and microcosmic salt, with effervescence. 



c. 22.0 grs. during their solution in vitriolic acid, effer- 

 vesced, and lost 7.8 grs. of carbonic acid =z 0.354. Thi& 

 solution was colourless, and afforded 26.8 grs. of arid vitriol 

 of zinc, which, redissolved in water, shot wholly into clear 

 colourless prisms of this salt. 



