CLVII. Analysis of a Cobalf Ore found in Western Ikdiu. By J. MIDDLETON,Esg. F.G.S. Pri?ic+al of the Hon. East India Compmy's College at Agra. BE1yG,engag.ed in analyses of the metallic ores of North-westein India with a view to the ascertainment of the constitutions of those most remarkable among them and also Mr. J. Middleton on a Cobalt Ore with the hope of detecting others whose existence in the couiitry has not heretofore been even suspected I am desi-rous of submitting to the Chemical Society the results of my iiiquit-ies whenever they appear to me of suEcient interest to justicv my troubling them with them. I may mention that should the Society desire any information from me on this or any other subject that I may be qualified and in a position to furnish I shall most gladly meet their wishes.The hilly districts of Rajpootanah are remarkably prolific inmetallic ores many of‘ these too exceedingly rich and abundant. Within a iiarrow compass in the indepdent state of Syepoore are to he found the tbllowing minerals :-Sulphuret of copper sulphate of copper sulphuret of co-balt alum. The native method of mining for the first of these ores and which is the same as that adopted for the others mag be interesting to some of’your members. 6‘ The mine of copper is very deep and difficult of access. The niiners eiiter with burning lamps on their heads and with chisels iron hammers and baskets in their hands. ’They dig out the ore with their chisels by the light of their I:tiiips aiid bring it up with great labour and difficulty to the surfhe.They then pound and grind it small in a mill after which they mix it with moist cow-dung and this mixture being made into balls is pliiced in the sun to dry. When this has beeii accomplished the Iiiunps are burnt after which they are not broker] up but being niixed with an equal quantity of char-coal and as much iron filings are put into a crucible and a strong hent kept up by blowing with a leathern bellows till the dross separates and the copper settles at the bottom iii the form of a solid disc. This product is again heated with charcoal until perfectly pure colxper is pwcluced*.” The rnineral possessing greatest interest amongst those above ei.umerated is the sulpliuret of cobalt.It is found iri the coppcv- mines in coiisitferable abuiidaiice and exists in a primitive schist in the form of bands and disseminated grains the colour of which is a steel gray inclining to yellow. The grains appear to be crystallized and are probably the cube and its derivatives. What is particularly remarkable in this ore is its purity so fir surpassing in this respect any that so far as I arn aware is to be met with anywhere else. The only suhtarice in combination with it after separation of the matrix is an irori pyrites which is however but niechanically mixed and so highly magnetic as to be readily removable by * This description is the translation of n native o:ie given to me with the minerals. foioul in IVrsfer*?rIdin. the magnet.‘I’he relative proportions in which these two exist are-Cobalt pyrites .... 90*78per cent. Iron ....... 9% ... The iron pyrites consists of black amorphous granules with-out metallic lustre and as above stated it is highly magnetic having at the same time the lorn specific gravity of 2.58. It gives 011 analysis-Iron ....... 62-27 per cent. Su I ph LI r ...... 37 -7s ... The analysis was carefidly made and repeated for verifica-tion so that notwithstanding the specific aravity is so much lower than that assigned as characteristic of?iron pyrites there can be no doubt siicti is the constitution of this constituent of tlie ore in question. ‘l’he cobalt pyrites exhibits the usuaI characteristic reac-tions generally sub,jttct to some modifications which do not tleserve notice as I tbund them to be niohtly owing to the Iiigh temperature at which my experiments were made one Iiowever is rattier rernarkzble and not sssigiiable to tliis cause but probably to the particiilar natural constitution of the iuineral wliich as I have found in other cases modifies the be1I Hv iou r of s LI bstan ces occasion a1 1y.Ferrcbcyanide of potassium produces in acid solutions a 1;lLiibh-peen precipitate which completely dissolves up in fi)rty-eight hours yovided the solution be not highly con- ceti tratecl to a brilliant emerald-green fluid which is not ;lff>cted by acids or by standing but the colour of which cl::iiiges to greenish yellow without precipitation by am-iiionia. By very careful and repeated analysis the reduction pro-cess having been adopted for the metal I found the propor-tion of the constituents to be taking the average,- Cobtilt ......64.64 per cent. Su I p h ur ...... 35.3 6 ... from which it is obvious the siil)stance is a snb-sulphuret that its constitution is Co S a rather remarkable result consider- ing that the iron coni~~ouncl doubtless of sin~iiltaneous forma- tion is different. ‘rtie cobalt pyrites has tlie specific gravity of 5*45. It is zised by Indian jewellers fi)r stniniiig .gold of‘a delicate rose-red colour; the modits opernridi wh:ch they follow I have beeii Linalde to lvarn; it is ;i secret ivith them which they are iitiwilling to dixlose.