MORSE. — SIUDIES ON FLUORITE. 605 



minerals, with especial attention to the probable conditions of tempera- 

 ture, pressure, and concentration of water vapor which existed on tbe 

 earth at the time the minerals were formed, and they suggest reactions 

 between water vapor, carbon dioxide, and the ferrous compouuds of the 

 rocks and minerals to explain the appearance of the gases evolved # 

 Ramsay and T ravers 38 also examined a number of minerals with the 

 same object in view. 



It is evident that two important questions are involved, — whether or 

 not the permanent gases can remain as such as inclusious in minerals, 

 and whether any conclusions as to the conditions existing on the earth at 

 the time the minerals were formed can be drawn from the inclusions 

 present in them. Travers 39 shows that it is doubtful whether carbon 

 monoxide, nitrogen, oxygen, and hydrogen can remain for a long time 

 included in cavities in minerals, and suggests that they may be formed 

 during the examination of the minerals as a result of the methods of 

 analysis. He shows that many minerals which yield both carbon 

 monoxide and carbon dioxide on being heated give only carbon dioxide 

 when the same mineral is decomposed by the action of an acid. 



Direct evidence on this point may be found in the analyses of Huttner, 40 

 who heated a number of minerals to 800°-850°, driving out air by means 

 of carbon dioxide and carrying the products of reaction along into the 

 receiving apparatus by means of the same gas. Hiittner expresses the 

 opinion that the hydrogen which he finds in all of his analyses is formed 

 by the reaction suggested by Gautier, i. e., by the action of the ferrous 

 and manganous compounds of the mineral with the water vapor which is 

 always present, and he further offers the opinion that the carbon monoxide 

 found results not merely from the reaction between carbon dioxide and the 

 ferrous compounds, as suggested by Gautier (1. c), but rather from the 

 direct reduction of carbon dioxide by hydrogen resulting from the above 

 reaction. Travers's conclusion that no carbon monoxide is produced 

 when the mineral is decomposed by the action of an acid is confirmed by 

 Hi'ittner's results obtained by the same method. 



In the special case of fluorite no extended series of analyses of the 

 included gases has been made. The very great difficulties involved in 

 the decomposition of this mineral by an acid and collecting the gases 

 evolved practically excludes this means of deciding whether the gases 

 found exist as such in the crystals or are formed during the progress of 



38 Roy. Soc. Proc, 60, 442 (1896). 39 ibid., 64, 130 (1898). 



40 Ztsch. anorg. Cliem., 43, 8 (1905). 



