238 Kraus and Hunt — Sulphur and Oelestite. 



analysis of the uppermost layer, characterized as Bed A by 

 Sherzer, was made. 



As already indicated, this rock is by no means homogeneous 

 and, hence, in order to obtain as near as possible the average 

 composition of the same, many chips were taken from a speci- 

 men of approximately the following dimensions, 4x5x6 

 inches. The specific gravity of most of the chips was deter- 

 mined and the following are some of the values obtained : 

 2-80, 2-87, 2-98, 3'17, 3*33, and 345. 



The methods pursued in this and the following analyses 

 were those recommended by Hillebrand.* Knowing that 

 much would depend upon the careful separation of the earth 

 alkalies, the utmost care was exercised in their determination. 

 The precipitates were in every instance tested spectroscopi- 

 cally and, if necessary, the extraction repeated until in each 

 case they could be considered free from contamination. We 

 may, therefore, regard the results obtained as very accurate. 

 They are as follows : 



Per cent. Eatio. 



SiO„ 0'58 



A1 -°- I 0'37 



CaO 25-18 0-44884 



MgO 18-11 0-44871 



BaO 0-13 0-00085 



SrO 7S6 0-07587 



Na 2 _. Oil 



K 2 0-05 



P 2 B 0-02 



CI 0-04 



C0 2 39-55 0-89886 



SO s 6-33 0-07907 



Organic matter 0-92 



H 2 S trace 



Total 99-25 



The percentages of the oxides of calcium, magnesium, 

 strontium, and barium, together with the carbon dioxide and 

 sulphur trioxide, are important. It is at once noticeable that 

 the amounts of strontium oxide and sulphur trioxide are rela- 

 tively high. A comparison of the combined ratios of the 

 oxides of calcium and magnesium with that of the carbon 

 dioxide, 



Mg o o( < :"8?i) ) } :C0 .(- 89886 ) = i:i -° 014 ' 



shows that the rock is essentially a dolomite and, in fact, a 



normal dolomite. We, thus, have quite conclusive evidence 



* Bulletins 148 and 176, U. 8. Geological Survey. 



