1873.] 



Major W. A. Ross on Jeypoorite. 



295 



(13) Three large selected crystals of Jeypoorite were added, one by 

 one, to a phosphoric acid bead of 50 mgrs. in an 0. P. These weighed 

 3'2 mgrs. They all at first emitted a few bubbles of gas (S0 2 ?), and 

 afforded yellow creamy streaks (S?) not unlike those of phosphate of 

 silver, but proved not to be due to that metal, by the test described in 

 par. 42 of " Pyrology," and a sooty-black oxide (Co ?), while the plati- 

 num wire was slightly corroded. The first two products were soon dis- 

 sipated ; the cobalt oxide dissolving, gave the glass a fine rose-tint in the 

 case of the first crystal. The second crystal coloured the glass a much 

 deeper red ; and when the third had been dissolved in the glass, it assumed 

 the splendid red-violet hue of cobalt (vide " Pyrology," par. 35). 



(14) It took exactly 2-5 mgrs. of pure cobalt oxide to give to a 50 mgr. 



P glass laid alongside of (13) on a sheet of white paper, and also viewed 

 with it by transmitted light, the same colour. 

 Therefore 



5 : 6*4 : : x (per cent.) ; and of 100, =83-2 per cent, cobalt. 



(15) It took 21 mgrs. of carbonate of soda to azurize bead (14), but 

 only 20 mgrs. to azurize (13) ; so that there was slightly more acid in the 

 former bead. 



(16) The bead (14) weighed, after the soda had been added, 77 mgrs., 

 while (13) bead weighed 75 mgrs. They had both been kept up to the 

 mark by the means mentioned in par. 78 of the paper on " Pyrology." 



(17) As this percentage of cobalt seemed too high compared with that 

 recorded in works on mineralogy from Middleton's analysis above cited, I 

 made the following second assay, in a manner slightly differing from the 

 preceding. In order also to guard against the possibility of loss of any 

 cobalt from its fusion in the form of arsenide with the red-hot platinum- 

 wire, the glass with a Jeypoorite crystal on its surface was manipulated 

 in such a manner that the lower surface of the bead just touched the upper 

 surface of the jet, in which position the ring of the platinum-wire never 

 even approaches a red heat, being kept comparatively cool by the action of 

 the superposed blast (par. 7, " Pyrology "), which cuts the heat off from it ; 



while sufficient heat is imparted to the P glass to dissolve most sub- 

 stances, which, even metals, cannot under these conditions attack or 

 combine with the platinum, although, lightened by the loss of volatile 



on bright silver foil with distilled water, gave a brown stain of AgS quite as strong as 

 that afterwards afforded by Jeypoorite, to which, therefore, if this soda had been used, 

 double the amount of sulphur it really contains might have been attributed. The same 

 soda fused on platinum wire gave no stain whatever to silver. 



A glass of pure boric acid fused in O.P. on this charcoal detects in its ash ("Pyro- 

 logy," par. 65) silica, lime (in considerable quantity), magnesia, and protoxide of iron ; 

 while soda, as above-mentioned, shows it to contain sulphur, or sulphuric acid, and 

 also shows its iron, which gives the soda a pale salmon-colour. The Government 

 gunpowder is, I believe, made of this charcoal. 



