STATES OF THE GASES. 



59 



volumes of nearly pure hydrogen. Many other metals behave similarly. 

 Non-metallic substances appear to possess this property in a lesser degree. 

 Porcelain occludes hydrogen, whether because of its porosity or solvent 

 qualities is not certain. Quartz is said to be penetrable, at high tempera- 

 tures, by the gases from the oxyhydrogen flame, 1 which points towards a 

 form of occlusion. 



In addition to hydrogen, other gases are occluded. Litharge, when in 

 the molten condition, dissolves hydrogen, carbon monoxide, and nitrogen, 

 of which it retains a portion on solidifying. 2 Cast iron, on cooling, retains 

 4.15 volumes of carbon monoxide, 3 which perhaps may be due to the for- 

 mation of iron carbonyl, Fe(CO) 4 , or similar unstable compounds. 



Analyses show that whenever metallic iron is present in notable quan- 

 tities carbonic oxide becomes an important constituent of the gas evolved. 

 The following analyses of the gases from various types of iron indicate 

 the proportions of hydrogen, carbon monoxide, carbon dioxide, and nitro- 

 gen which this metal may absorb, given in percentages of the total gas 



content : 



TABLE 36. 



1 Cited by Cohen, Meteoritenkunde, p. 181. 



2 Cited by Lane, Bull. Geol. Soc., vol. 5 (1894), p. 264. 



Whatever may prove to be the ultimate significance of occlusion, and in 

 whatever condition these gases are stored in the iron, whether it be in the 

 nature of a solution, as Mendeleef has suggested, or as definite compounds- 

 hydrides, nitrides, and carbonyls the fact remains that these gases exist 

 within the metal and are in many respects similar to the gases locked up in 

 iron meteorites. Fresh iron borings from the interior of a metallic meteorite 

 have usually been assumed to be free from any hydration or carbonation 

 from terrestrial agencies, and so have been held to contain true meteoritic 

 gases. Some question respecting this belief has arisen from certain analyses 

 which, as we have seen, indicate secondary action. 4 In addition to this 

 the gases actually received in the laboratory may not represent the original 



1 Poynting and Thomson, Properties of Matter, p. 204. 



2 Le Blanc and Cailletet, cited by Violle, Cours de Physique, t. 1, p. 922. 



3 Daniell, Principles of Physics, p. 327. 



4 Experiments with the Toluca iron ; Analysis No. 108. 



