502 



Action of heat 

 ©n it. 



Dissolved in 

 Ditric acid. 



Jn murialic. 



Oxide of iron 

 ic manganese. 



Carbonate of 



EXAMINATION OF A CALCAREOUS STONE. 



Exp. 1. A. One hundred grains of thunder-pick in corirse 

 fragments exposed in a platina crucible two hours and a 

 half to a moderate heat lost only four grains, but after- 

 wards exposed to a much higher temperature for an hour 

 lost 42*90 grains. 



B. One hundred grains in one piece exposed in a porce-- 

 lain crucible two hours to nearly a white heat lost 45*90 

 grains. 



A and B. The residue of these two operations, amount- 

 ing to 112'20 grains, were exposed in a porcelain crucible 

 for four hours more to an intense white heat. When the 

 crucible was taken out and examined, only 102 grains 

 could be collected, as the remainder had united to the cru- 

 cible, but from its apparent quantity no loss of any conse- 

 quence could have been sustained. The crucible as well as 

 its Wedgwood cover had suffered a commencement of fu- 

 sion, and they could not be separated v»^ithout breaking. 



JExp. 2. A. Wishing to ascertain nearly the quantity of 

 nitric acid requisite to dissolve a certain quantity of thunder- 

 pick, I weighed 100 grains of it in fragments, and intro- 

 duced to it 100 grains of pure nitric acid of the specific 

 gravity 1'431, and added more acid by ten grains at a time, 

 till the whole was dissolved. Having thus found the quan- 

 tity of acid necessary to dissolve 100 grains of thunder-pick, 

 I placed it on the balance, and equipoised it on the other 

 scale; 100 grains of thunder-pick were then conveyed into 

 the acid, and the weight of the carbonic acid gas was found 

 to be 42-40 grains. 



B. I repeated the above experiment, substituting a quan- 

 tity of muriatic acid of the specific gravity of 1*149 with 

 100 grains of thunder-pick, and nicely adjusting the ba- 

 lance as before, found the weight of the carbonic acid gas 

 given out to be 43 grains. 



C. The nitric solution (A) being now filtered became 

 nearly colourless, aud left on the filter the colouring matter 

 of the thunder-pick. I believe a little oxide of iron and 

 manganese, which, when dried, weighed 0*40 of a graiin. 



D. The filtered solution being treated with carbonate of 

 potash, carbonate of lime fell down, which when collected 

 and ignited in a crucible weighed 96 grains* 



E. To 



