No. 1.] WRIGHT — GASES IN SMOKY QUARTZ. 17 



As was raentioaed in a preceding paragraph, no evidence of 

 the presence of a hydro-carbon compound was discovered in the 

 examination of the gas which had passed slowly through the 

 cooled tubes. The tubes themselves, however, contained what 

 appeared like minute drops of some oily substances, so small as 

 to be scarcely visible without a lens, and quite insuflScient for ex- 

 amination. Tn order to investigate this point more satisfactorily 

 as also to obtain a greater quantity of the residual gas left by 

 absorption of the carbon dioxido, an experiment was made as 

 follows: A bolt-head of porcelain, glazed interiorly, and having 

 a capacity of about 300 cubic centimeters, was employed for the 

 reception of the quartz, of which 196 grams, making 7'5-4 cubic 

 centimeters, were used. It was arranged that after the air had 

 been pumped out, the gas from the quartz should pass through 

 a strong solution of potassic hydrate contained in a large U-tube, 

 all connections being made with fused glass joints as before. The 

 greater portion of the carbon dioxide was thus absorbed. Unfortu- 

 nately just at the close of the operation a slight crack in the por- 

 celain vessel admitted some air, but the tube leading to the pump 

 was sealed immediately, so that the amount mixed with the gas 

 was not too great to permit a quantitative examination of the 

 gas to be made. A portion of the latter being transferred 

 to the eudiometer, and just sufficient electrolytic gas being ad- 

 mitted to ensure combustion, the volume of the gas after explosion 

 was found to be considerably increased, with the production of 

 carbon dioxide. Repeated tests gave uniformly the same result, 

 but the expansion was greater at first than after the gas had been 

 kept for two days iu the pump. This must be regarded as evi- 

 dence of the presence of the vapor of some condensable hydrocar- 

 bon havino; a lar^-e number of carbon atoms in the molecule. 



The quartz on heating entirely loses its color, the coarse powder 

 which is left being almost snow-white. Now, in the experiment 

 just described, a dark brownish deposit was formed in the tube 

 leading from the bolt-head, and the potash solution after the 

 passage of the gas had become brown, the color being almost 

 exactly the same as that of the quartz before the heating. After 

 standing a day or two a small amount of a dark brown, nearly 

 black, substance separated out as a precipitate and the liquid 

 lost it color. The potash solution was now decanted and the dark 

 deposit examined. Treated with alcohol it dissolved but partially. 



Vol. X. B No. 2. 



