HISTORICAL SKETCH. 5 



spectrum, which was found to show the presence of much carbon dioxide, 

 together with water and a very weak trace of hydrogen. The presence 

 of the hydrogen line, however, the authors were inclined to attribute to 

 water-vapor. 



Further researches upon the critical point of the gas in mineral cavities, 

 carried on by Hartley, 1 yielded results varying from 26 to 34 C. The 

 lowering of the temperature he ascribed to the presence of some incon- 

 densable gas, perhaps nitrogen, while he believed that the raising of the 

 critical point observed in some of the quartz specimens was due to hydro- 

 chloric acid. 



Forster 2 and Hawes 3 investigated smoky quartz, the former distilling 

 from the Tiefengletscher crystals a brown fluid of an empyreumatic odor, 

 giving reactions for ammonia and carbonic acid, from which he concluded 

 that the coloring matter of smoky quartz was due to a nitrogenous hydro- 

 carbon, decomposable by heat; the latter made a microscopic study of the 

 liquid carbon dioxide in the bubbles of the cavities. 



Investigations which have opened up a broader field were begun by 

 Graham 4 in 1867 upon the Lenarto meteoric iron. By submitting a strip 

 of the iron to a red heat in a vacuum for 35 minutes he obtained 5.38 cubic 

 centimeters of gas from 5.78 cubic centimeters of the metal. Heated for an 

 additional 100 minutes, there were evolved 9.52 cubic centimeters of gas 

 having the following composition: H 2 , 85.68; CO, 4.46; CO 2 , none; N 2 , 9.86. 



As this meteorite yielded about three times its volume of gas, and 

 since "it has been found difficult, on trial, to impregnate malleable iron 

 with more than an equal volume of hydrogen, under the pressure of our 

 atmosphere," Graham drew the inference that this meteorite came from a 

 body having a dense atmosphere of hydrogen gas. By the same process 

 Mallet 5 extracted 3.17 volumes of gas from a Virginia meteorite. His 

 results were in accordance with those of Graham: H 2 , 35.83; CO, 38.33; 

 CO 2 , 9.75; N 2 , 16.09. 



Wohler 6 heated to redness some of the metallic granules from the iron 

 basalt of Ovifak, Greenland, obtaining more than 100 volumes of gas which 

 burned with a bluish flame (mostly carbon monoxide mixed with a little 

 of the dioxide). His results, however, were vitiated by having used an 

 iron combustion tube. 



Pursuing the method adopted by Graham and Mallet, A. W. Wright 7 

 conducted a series of experiments on meteorites, which have remained to 

 the present day the source of most of our knowledge of the gas content of 

 these interesting bodies. Wright's chief contribution lies in his two tables 

 showing that there is a marked difference between the gas contents of the 

 iron and stony types of meteorites; for while, in the former, hydrogen is 



1 W. N. Hartley, Jour. Chem. Soc. (1876), vol. 2, pp. 237-250. 

 2 A. Forster, Pogg. Ann., 143 (1871), pp. 173-194. 

 3 G. W. Hawes, Am. Jour. Science, vol. 21 (1881), pp. 203-209. 

 4 Thos. Graham, Proc. Roy. Soc., vol. 15 (1867), p. 502. 

 5 J. W. Mallet, Proc. Roy. Soc., vol. 20 (1872), pp. 365-370. 

 6 F. Wohler, Pogg. Ann., 146 (1872), pp. 297-302. 



7 A. W. Wright, Am. Jour. Science, vol. 9 (1875), pp. 294-302 and 459-460; vol. 11 

 (1876), pp. 253-262; vol. 12 (1876), pp. 165-176. 



