50 METALLURGY. 



others, from its constituting nine parts in twenty of chalk and 

 other calcareous earths, chalky acid j and from its being destruc. 

 tive of flame and animal life, some have denominated it mephitic 

 air. The weight which was thus lost by dissolving the Derbyshire 

 calamine in an acid, corresponds sufficiently with that which the 

 workmen observe to be lost during the calcination of that mineral ; 

 to that these processes mutually confirm each other. 



Bergman observes that 100 grains of Flintshire calamine lost by 

 calcination thirty four grains* : now this quantity corresponds, as 

 much as can be expected in things of this sort, with the loss which 

 I observed during the solution of 120 grains of the Derbyshire 

 calamine; for if I had dissolved only 100 grains, the loss would 

 have been 33^. The same author, however, remarks that 100 

 grains of Flintshire calamine, when dissolved in an acid, gave 

 only twenly-eight grains of air : and he thinks that six grains of 

 water are contained in every 100 grains of that sort of calamine ; 

 for he takes the difference which he observed between the weight 

 of air obtained by solution, and the loss of weight sustained during 

 the calcination of 100 grains of calamine, to be owing to the water 

 which is dispersed during the process of caldnationt. Fontana 

 obtained 190 grains of fixed air from 576 grains of Somersetshire 

 calamine : according to the same proportion, had he used only 100 

 grains, he would have had thirty. three grains of fixed air, instead 

 of the twenty. eight which Bergman got from the Flintshire cala. 

 mine j I say instead of the twenty. eight, for I am inclined to 

 think that the Derbyshire, Flintshire, and Somersetshire calamities 

 do not differ much from each other in the quantity of air which they 



* Vol. II. p 327. 



-r Bergman has used (he same method of analysing other substances con- 

 taining fixed air, particularly calcareous earths. He found that 100 grains of 

 transparent calcareous spar gave, by solution in an acid, thirty-four grains of 

 fixed air, and lost by calcination forty-five grains; tin- difference, eleven 

 grains, he says is water; which, though expelled by the fire, remains mixed 

 with the acid ; and hence 100 grains ofx such spar contain fifty-five grains of 

 lime, thirty-four grains of fixed air, ai.d eleven grains of water. 1 have a 

 little difficulty in admitting this mode of inferring the quantity of wafer con- 

 tained in these bodies: I do not absolutely deny the justice of it; but I 

 hesitate concerning it; because, from experiments which I made with nil the 

 care I could, I found that fine Irinsp.irrnt spar, very white marble, &c. 

 as nearly as could be estimated, the sauc weight, whether they were dissolved 

 in an acid, or calcined in a strong fire. 



