74 J. P. Cooke on Danalite from Rockport, Mass. 
alumina could not with certainty be detected by any known 
tests. The precipitate of glucina perfectly redissolved in an 
excess of carbonate of ammonia, and no crystals of alum could 
be obtained from a solution of the sulphate when treated in the 
usual way with an excess of —_ of potash, although they 
were sought for with a microscop 
As the sulphid of hydrogen ehiatag is evolved from the metal- 
lic sulphids, when the mineral is decomposed by waa 
acid in a closed flask, would necessarily reduce all the ir 
present to the condition of proto-chlorid, the following el 
ment was made to determine the original condition of the iron 
in the mineral. It is evident that any such reduction must be 
attended with the separation of free sulphur, and hence sulphur 
was sought for in the products remaining in the flask after the 
decomposition was finished. The sulphid of hydrogen and the 
greater part of the free hydrochloric _ having been first ex- 
. pelled, the residuo ee boiled with an excess of concentrated 
nitric acid, an o trace of seiner acid was found it was 
— ‘that the i iron in the mineral, not united with sulphur, 
all in the condition of protoxyd, The same experiment 
iso proved that none of the varieties of iron pyrites could be 
present in the mineral in distinct grains, as was at first suspected; 
and this conclusion was confirmed by the fact that a powe 
magnet failed to attract any portion of the mineral, even when 
reduced to the finest powde 
In the quantitative analysis no unusual methods were em- 
ployed. - The mineral was decomposed in a sealed flask as 
Lastly , the sear which now comer in solution as sip 
' We have never succeeded in ety eed the whole of the glucina as 
——o although carefully attending to all uations which have been aa 
d by other analysts. “But alumina is perfectly recipitated when the necessary 
ee are observed, 
