214 A. W. Wright— Gases in Smoky Quartz. 
the examination of the gas which had passed slowly through 
the cooled tubes. The tubes themselves, however, contaie¢ 
% 
experiment was made as follows: A bolt-head of poreeltiag 
portion of the carbon dioxide was th 
gas after explosion was found to be considerably increas 
with the production of carbon dioxide. Repeated tests ae 
i eater al 
powder which is left being almost snow-white. 
experiment just described, a dark brownish depo 
almost exactly the same as that of the quartz before the heat- 
ing. After standing a day or two a small amount of a dar! . 
brown, nearly black, substance separated out as a precipita’ 
