NATURAL SCIENCES OF PHILADELPHIA. 36T 



The fracture is uneven conchoidal. Opaque in the amorphous, 

 subtranslucent when crystallized. 



The lustre is slightl}' resinous. 



Tlie color of the crystallized mineral is faint j'ellow. 



The amor|)hous is more 3'ellow, and, on some parts, it is even 

 brownish-^-ellow. 



The streak is dull 3'ellow. The powder of the mineral in a 

 thick layer on a white surface is straw-3'ello\v. 



The cohesion is not strong ; it yields easil}^ to the point of the 

 knife, producing angular pieces, brittle. 



The hardness is equal to fluorite, or 4. 



Specific gravity = 3.598. 



The mineral has no effect on the magnetic needle. 



Pyrochemical test: In the glass tube closed on one end it affords 

 water and a white sublimate. On charcoal, metallic globules and 

 a white incrustation, which deposited far from the test, and on 

 stopping the fire, rising fumes. Borax affords, in the oxidizing 

 and in the reducing flames, beads, Avhich are yellow while hot and 

 colorless after cooling. 



In nitric acid the substance is not soluble. H^'drochloric acid 

 dissolves it, except quartz, which is an impurity. 



Caustic potassa decomposes the mineral, changing the 3'ellow 

 powder apparently into red. The liquor, however, then contained 

 antimoniate of potassa, which, when poured into a mixture of 

 iodide of potassium and h3'drochloric acid, liberated iodine. The 

 red powder I ascertained to be sesquioxide of iron. 



The quantity of the water I determined by the loss on heating 

 the substance to a low red heat. 



For the quantitative determination of the antimonic acid I 

 fused the substance with carbonate of soda and sulphur; extraeted 

 the black mass with water, washed, precipitated the sulphuretted 

 antimon3' with h3-drochloric acid, and, after drying and weighing 

 tlie mixture of sulphuret of antimony and sidpliur, I analyzed an 

 aliquot part of it, according to Bunsen's process. (It appears 

 that the adopted process chosen for the determination of the anti- 

 mon3' is one of the best known ; yet the loss is always greater than 

 it ought to be for close work. It would be a good gift if anybod3' 

 could present us with a process for the determination of anti- 

 mony in which the weighing of the sulphuret of antimony and 

 sulphur on a dried paper filter could be avoided.) Tiie iron antl 

 the quartz were determined in the usual wa3'. 



Tlie result of the analysis was 



Bb 43.96 per cent. 



Ve 31.85 " 



H 15.26 " 



Quartz 8.84 " 



Loss . . . , . . 1.09 " 



100.00 



