294 



Major W. A. Ross on Jeypoorite. [May 15, 



mehfcs. These crystals weigh from 1*0 to *7 milligram ine each*; but 50 

 of theia crushed in a Plattner's steel mortar, produced a powder weighing 

 only 36 mgrs. This powder is blue-black and seinimetallic, like that 

 made from galena ; it adheres to every thing it touches, soiling paper like 

 graphite — a property not possessed by the crystals. Neither the roasted 

 powder nor the crystal is magnetic. 



(9) Professor Miller has favoured me with the following determination 

 of the crystalline form : — 



" These crystals beloug to the cubic system. The simple forms are : — 

 the cube 10 0; the octahedron 111; and a hemihedral form with pa- 

 rallel faces II 1 2. The angles between normals to the faces are : — 



1 0, 1 90 6 



1, 1 90 



1 0, 1 90 



10 0, 111 54 44 



1 0, 1 2 63 26 



1 0, 1 2 26 34 



111, 1 2 39 14." 



(10) Roasted on an aluminium plate (vide my paper on " Pyrology," 

 Proceedings of the Royal Society, No. 137, vol. xx. par. 89) a very slight 

 smell of S0 2 is at first perceived, after which the powder very slowly 

 changes its semimetallic appearance for the sooty black one of protoxide 

 of cobalt ; for sulphides, arsenides, &c. thus roasted do not " sinter." 

 No green indications of nickel are given (" Pyrology," par. 90). 



(11) Roasted through a platinum-foil tray {vide "Pyrology," par. 83), 

 three crystals of Jeypoorite ground into a paste with double the weight of 

 pure Pe 2 3 (a Preiberg reagent) caused the steel leg of the forceps to be 

 covered thinly with a sublimate disposed in leopard-like ^Ol^^D^^^ 

 spots, white {antimony), with an orange tinge round their Jy 2 * 



edges (arsenic). 



(a) To make certain of this reaction, a small trace of Sb 2 3 was mixed 

 intimately with a quantity of the Preiberg rust and water ; and when 

 carefully ignited on a new platinum tray, it deposited exactly similar 

 spots on the forceps, only white on the edges as elsewhere. 



(12) Pused with soda on a platinum wire; and the mass placed on 

 silver foil with water, three crushed crystals of Jeypoorite gave a mode- 

 rately brown stain of sulphide of silver, showing that it contains a small 

 quantity of sulphur*. 



* There are, however, much smaller ones in the residue from (4). 

 t In testing my carbonate of soda previously to using it with Jeypoorite for the sul- 

 phur and sulphuric-acid test of Berzelius on silver foil, I fused the soda on a " mortar " 

 of beautiful-looking close-grained charcoal from the Government powder-works at 

 Waltham Abbey. The fused soda- mass, dug out as Berzelius recommends, and placed 



