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The stones from Benares are covered with atiiin crust of a deep black colour, without anylustre, and sprinkled over with small asperitieswhich cause it to feel like fish-skin. Internallythey are of a greyish ash colour, and of a gra-nulated texture, like that of a coarse grit-stone.They are evidently composed of four differentsubstances. One of these (and that whichforms the greatest part of the entire mass) isin the form of distinct concretions, more or lessglobular, varying in magnitude from the sizeof a small pin’s head to a pea: their colouris grey, inclining more or less to brown, andthey are perfectly opake. They are easily fran-t gible in all directions, and display a compactconchoidnl fracture with a slight degree of lustreresembling enamel, the hardness is about equalto that of glass, and they give a few feeblesparks with steel. Another of the substancesis reddish yellow iron pyrites, which when pul-verized becomes black ; it is not attractable bythe magnet, and is irregularly dispersed throughthe substance of the stone. The third sub-stance is iron in minute particles, and perfectlymalleable : its proportion to the whole, as esti-mated from pulverizing the stone and separatingthe iron by means of a magnet, is about 2 percent. These three substances are held togetherby a fourth, which is soft, of an earthy consis-tence, and a grey colour. The black crust bywhich the surface of the stone is coated, al-though of inconsiderable thickness, affordsbright sparks when struck with steel, and ap-pears to consist principally of magnetic blackoxide of iron. The specific gravity of the entirestone is 3 . 35 .

The stone from Yorkshire presents similarconstituent parts with that from India , with thefollowing exceptions. The distinct concretionsare smaller, and of a more irregular figure.The proportion of iron pyrites is less; that ofthe metallic iron is considerably greater, amount-ing to S or 9 per cent, and the iron itself insteadof being in minute distinct grains was in ir-regularly shaped pieces, some of which weighedseveral grains. The earthy part of the stonehas rather more consistence than that of theformer specimen, and greatly resembles in ap-pearance decomposed felspar or kaolin. Thespecific gravity of the stone is 3.5.

The stone from Sienna was black externally,and internally was coarsely granular like thespecimen from Benares. Its specific gravitywas 3.41. In it might be perceived the sameglobular concretions, the same kind of ironpyrites, and the same grains of metallic iron,

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the proportion of this last somewhat exceededthat afforded by the specimen from Benares.The same kind of grey earthy substance servedto connect the different parts together. Bur,beside the ingredients above mentioned, therewere a few globules of black magnetic oxide ofiron, and a single globule of a pale greenish-yellow colour; this latter was completcdy trans-parent, had a perfectly vitreous lustre and frac-ture, and in hardness was rather inferior to cal-careous spar.

The stone from Bohemia greatly resemblesthat from Yorkshire . In it may be observedthe same grey substance both in globular andirregular concretions, also the same particles ofmetallic iron, and the same kind of earthy sub-stance connecting together the other parts. Itdiffers however from the others in the particlesof pyrites being so small as not to be visiblewithout the help of a lens ; and in the propor-tion of metallic iron amounting to about 25 percent, of the entire mass. Its specific gravitywas 4.28.

The ingredients being the most distinct inthe specimen from Benares, was the induce-ment to Mr. Howard to commence his chemi-cal examination with this. Some pieces of py-rites to the amount of 16 grains being carefullypicked out* from among the other substanceswere digested at a low heat with diluted mu-riatic acid. A small quantity of suiphuretedhydrogen was disengaged, and after a time allthat remained undissolved was earthy matterto the amount of two grains (thus reducing thereal quantity of pyrites operated on to 14 grs.)and about 2 grains of sulphur. The solutionwas saturated with ammonia, upon which aprecipitation of oxide of iron took place, andthe supernatant fluid acquired a violet purplecolour ; this latter, having previously beenfound to contain not copper but nickel, wasdecomposed by sulphuretted hydrogen. Theoxide of iron after ignition weighed 15 grains,and the sulphuret of nickel being reduced to anoxide by calcination weighed something morethan one grain. From these data Mr. Howardconsiders the pyrites as composed of JOi iron,

I nickel and 2 sulphur, estimating the per-oxideof iron to contain 55 per cent, of metal. Onexamination however it appears that certaindifficulties or mistakes adhere to these results,which make the analysis by no means so correctas it appears to be. First, Mr. FI. from hisown experiments states that 100 parts of ironafford 145 grains of oxide by solution in mu-riatic acid precipitation by ammonia, and sub-