26 M. Lowe's Analyses of 



The actual loss by heating, after subtracting the hygroscopic 

 water, can be assigned only to the basis, that is the gelatinizing 

 portion ; for it is well known that the magnetic iron-ore and the 

 augite contain no water. The iron contained in the soluble 

 portion was considered in the calculation as a black oxide. 



In the investigation conducted in this manner, 6.0775 grm. 

 of basalt were reduced to the finest powder ; and of this quan- 

 tity 3.3782 grm. were insoluble in muriatic acid. The soluble 

 portion therefore amounted to 2.6993 grm. The silica amount- 

 ed to 0.9465 grm. The alumina and oxide of iron were preci- 

 pitated by ammonia, and sepai-ated by caustic potash ; the alu- 

 mina was determined by means of carbonate of ammonia, while 

 the oxide of iron was determined by succinate of ammonia, the 

 former amounting to 0.7015 grm., and the latter to 0.2905, 

 which, when calculated as black oxide, yielded 0.2805 grm. 

 The lime precipitated by oxalic acid yielded 0.2546 grm., and 

 the saline residue obtained by evaporation to perfect dryness, 

 was found to contain 0.3367 soda and 0.0348 potash. 



Of the insoluble portion 2.428 grm. were fused with three to 

 four times the weight of carbonate of soda. The silica thus 

 obtained weighed 1.165 grm. ; the alumina and oxide of iron, 

 separated as above, amounted respectively to 0.221 and 0.401 

 grm. (the latter considered as black oxide) ; the lime z= 0.350 

 grm. ; and the magnesia ascertained by means of carbonate of 

 potash, as well as by phosphate of soda, gave as the amount 

 0.315, including a trace of manganese. We have therefore for 

 the soluble portion the following composition : — 



Oxygen. 



100.68 



Leaving out the black oxide of iron, which is to be regarded 

 as a disseminated magnetic iron-ore, we have the following pro- 

 portions of the constituent parts :— 



