A, A. Julien on Minerals of the Key of Sombrero. 371 
were thrown down as ammonio-phosphate. In the filtrate the 
remainder of the phosphoric acid was precipitated with the 
usual sulphate of magnesia solution. The filtrate was evapo- 
tated to a small bulk, digested in a flask with nitric acid until 
the complete expulsion of all chlorine, evaporated to dryness in 
a platinum dish, and calcined to perfect whiteness. The residue 
(excess of magnesia from the reagent) was redissolved in hydro- 
chloric acid, the alumina and the oxyd of iron precipitated with - 
aqua and carbonate of ammonia, and, after weighing, the iron 
redissolved and determined volumetrically, if desired. In the 
filtrate the alkalies if present were separated from the excess of 
magnesia. 
In another portion of material, the water was determined as 
already explained, the ignited residue dissolved in nitric acid, 
and the chlorine and sulphuric acid successively estimated by 
additions of nitrate of silver and of nitrate of baryta. 
4. Metabrushite—This new mineral has been observed to oc- 
ity and attached in microscopic crystals to many small rootlets 
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length and half an inch in breadth, The crystals are usually 
lusterless, unlike the prisms of brushite. ‘I'he planes of cleay- 
age are the same as in that mineral and in selenite, but are more 
imperfect. No massive specimens have yet been discovered. 
Its characters are as follows : ae 
. =2°75. Sp. gr. (with large crystals and distilled water at 
60° F.) =2-288, 2-356, and 2°362. Luster vitreous, inclining to 
pearly, splendent on cleavage faces parallel to the clino-diagonal 
ti hat resinous on surfaces of irregular fracture. 
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In one assay the total loss of water by ignition was at once 
| ’ determined, and in three others, as in brushite, the loss at suc- 
