18 THE CANADIAN NATURALIST. [Yol. X. 



communicating its color to the liquid, and taking on a tarry con- 

 sistency. On evaporating the alcohol, the substance was volatilized 

 by more intense heat, with a strong bituminous odor, very much 

 like that o;:iven off by cannel coal when burnins;. The brown 

 deposit in the tube also gave off the same odor when strongly 

 heated. These results imply that the smoky color of the quartz 

 is due to the i^resence of a hydrocarbon of the nature of bitu- 

 men, which is driven off by heat, and the partial decomposition 

 of which, at the high temperature reached, accounts for the 

 heavy hydrocarbon found in the residual gas, or condensed upon 

 the walls of the cooled tubes. These facts, moreover, are entirely 

 in harmony with and confirm the conclusion of Forster* from 

 an examination of the remarkable smoky quartz from the canton 

 of Uri, that the color of the latter is due to the presence of some 

 volatizable hydrocarbon, though they do not directly connect the 

 ammonia with the latter, as his observations appear to do. 



After the operation just described had been concluded, some 

 pure distilled water was introduced into the bolt-head, and after 

 standing for some time was then withdrawn. Tested with argen- 

 tic nitrate it gave a considerable precipitate of argentic chloride, 

 while when examined spectroscopically it afforded satisfactory 

 evidence of the presence of sodium, but of no other metal. The 

 water previously examined was found to be free from both 

 chlorine and sodium. The bolt-head had been scrupulously 

 •cleansed before use, and great care was taken in this, as in all 

 the experiments, to prevent contact of the quartz with things that 

 might communicate to it any impurity. This result would indi- 

 cate that the cubical crystals observed by Mr. Hawes in some of 

 the cavities were chloride of sodium. Search was also made for 

 chlorine or chlorine compounds in the gas. A quantity of this 

 freshly liberated was passed through distilled water. This, on 

 the addition of argentic nitrate, was very slightly clouded, making 

 the existence of a trace of some chlorine compound probable. 

 Not unlikely a minute proportion of ammonium chloride is among 

 the contents of the cavities. 



The quantitative relation of the water to the gases obtained 

 from the quartz may be made more evident if calculated for a 

 temperature of 100° C. at which the former would be entirely 

 converted into vapor. Taking the amount of water per cubic 



Pogg. Ann., cxliii, 113, 1871. 



