W. T. Schaller — Composition of Hulsite and Paigeite. 545 



present in the above sample No. 2 can be calculated. The 

 amount of ferric iron belonging to the borate being thus deter- 

 mined, the amount belonging to the magnetite is found, and 

 deducting the proper amount of FeO to form FeO.Fe 2 3 , the 

 ratios reduce to the figures given beyond, which represent the 

 composition of the magnetite-free hulsite. 



The results obtained for the analyses of sample No. 3 are 

 given below. Though considerable insoluble gangue was 

 present, magnetite was entirely absent. The results shown 

 under la were made on a small sample of still impurer material 

 aud is chiefly of value for the determination of the tin, as the 

 value confirms the other figures given for tin. The ammonia 

 precipitate for sample la was not determined, as it was used 

 for various qualitative tests • and the calcium precipitate was 

 accidentally lost. The figures given under la are not taken into 

 the average. The higher value for the boric acid under col- 

 umns 1 and 2 is taken in the average instead of the mean of 

 the two values, as the second determination given is believed 

 to be low. 



Analyses of sample No. 3, hulsite. 



la 1 2 3 Average 



FeO . 27-71 27*71 



MgO 3-62 4-13 4*45 4*29 



CaO _._ 7-98 9-82 9'54 9*11 



Fe 2 3 1 15-21 



Total iron as Fe 2 3 __ 46-30 45-67 



Sn0 2 6-13 6-85 7'15 7*20 7-07 



B„0 3 9-20 8'27 9-20 



Insoluble.. 27*42 19-92 17*52 18*44 18*63 



H 2 0, CO,, Si0 2 , Al 2 O s diff 8-78 



10000 

 From the figures given above for the average analysis the 

 ratios were calculated with the following values : 



Eatios of analysis of sample No. 3, hulsite. 



FeO _ -385) 10-47 



MgO -107 j 



Fr 2 3 -095 2*02 



Sn0 2 __ -047 1-00 



B 2 3 -131 2-79 



The analyses of samples No. 2 of paigeite, as given beyond, 

 give an indication of the amount of calcium oxide which may 

 be derived from the gangue. For 15 per cent insoluble matter 

 the calcium oxide content is about 4 per cent. If this ratio 

 remains fairly constant, there should be, in the above analysis 

 of hulsite sample No. 3, about 5 per cent of lime obtained 

 from the gangue. This would leave approximately somewhat 



Am. Jour. Sci. — Fourth Series, Vol. XXIX, No. 174. — June, 1910. 

 36 



