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



o 



and upon these rested a loose plug of calcined asbestus. The 

 quartz, broken into fragments of such a size as to permit their 

 entrance, was dropped into the tube, filling it to within 10 or 12 

 centimeters of the mouth. When heated in a Bunsen flame, the 

 whole of the material could be brought to the requisite heat 

 without causing any perceptible elevation of the temperature of 

 the cement joints. This receptacle, when charged, watj connected 

 by means of the glass tube with a Sprengel pump, all joinings of 

 the glass being made by fusing, and the whole was easily ren- 

 dered absolutely free from leakage. 



The pump having been kept in action until no gas appeared 

 to pass down, heat was cautiously applied to the tube, and gradu- 

 ally increased until a little gas was liberated from the quartz. 

 When this had been thoroughly pumped out, removing thus the 

 last portion of air, the heat was again applied and continued until 

 the cessation of the decrepitation showed that no more gas could 

 be obtained. The mercury was then set running in the pump 

 carrying the gas into the measuring tube used for the analysis. 

 A preliminary examination showed the greater portion of the gas 

 to be carbon dioxide, the remainder apparently consisting chiefly 

 or wholly of nitrogen. A considerable amount of water was also 

 found to be present. In the succeeding operations this was 

 collected ibr examination by causing the gas as it issued to pass 

 through a U-tube of small caliber which was placed in a freezing 

 mixture. As the temperature of the refrigerating mass was such 

 as to reduce the tension of vapor to less than one millimeter, 

 nearly the whole of the water was thus retained. 



For the more careful analyses two portions of the rock were 

 selected representing the greatest difi'erences in the material. 

 The first. No. 1, was of a light gray color, somewhat milky in 

 appearance, and contained many cavities easily visible without 

 the aid of a lens. The weight of the material employed was 21-70 

 grams, which, divided by the specific gravity 2*63, gives for 

 the volume 8*25 cubic centimeters. The second portion was of 

 the darker variety having a smoky brown color, appearing nearly 

 black in large masses. The gas cavities in this were not so 

 conspicuous, and apparently were less numerous. The amount 

 of the material placed in the tube for examination was 19-49 

 grams, and the volume 7-41 cubic centimeters. This portion is 

 designated as No. 2 in the following paragraphs. The total 

 quantity of gas collected from No. 1 was 13-61 cubic centimeters, 



