S I L

S I L

( 300 )

obtained by procefs f. It may be added, as afurther proof of the amount of this fait beingerroneoufly dated, that 42 grains of muriaticacid (contained in 116 grains of muriated pot-afh) indicate 253 grains of muriated filver, whichis impoffible, the whole amount of the ore beingonly 200 grains. It is probable therefore thatthe following corrected flatement of the contentsof this ore is nearer the truth than that quotedabove, viz.

68.2 £ Silver7.36 Oxygen

15.02 Muriatic acidf 1 6. Oxyd of iron1.75 Alumine0.5 Sulphuric acid

98.88

2. Red Silver . d This ore was analyfed by

Klaproth in the following manner.

a. Five hundred grains being very finely pul-verized, were digefted for feveral hours at a lowheat, with 6 times their weight of ftrong nitricacid and water : a further quantity of water was 'then added, and the liquor was made to boil.The nitrous folution being poured off, the un-diflblved refidue was treated with an equalportion of acid as at firft, and managed in thefame manner: the whole was then thrown onthe filter, and the infoluble matter was welledulcorated.

b. The two nitrous folutions with the wafh-ings being added together, were reduced byevaporation to i of their bulk, and the remain-ing liquor depofited by cooling a confiderablequantity of greyifh-white cryltals of fulphatedfilver. The nature of thefe cryftals being afcer-tained, fome water was added to the fupernatantliquor, and by a gentle heat the whole was re-diffolved. The folution was then combined withmuriatic acid as long as any precipitate was pro-duced, and by this method muriated filver wasobtained, which, when edulcorated and dried,weighed 391.5 grains.

c. The fluid from which the above precipitatehad been obtained, was then reduced to a fmallbulk by diftillation, in confequence of which itbecame turbid and depofited 1 grain more ofmuriated filver: nothing now remained in theliquor except fome fulphuric acid.

d. The portion infoluble by nitric acid (a)weighed 202 grains, and was digefted in aquaregia, confifting of 5 parts muriatic acid and 1of nitric. After the action of this menftruum

there remained 65 grains undiflolved, whichrefidue after being duly walked and dried, wasexpofed to a gentle heat, in confequence ofwhich the fulphur burnt off, leaving behind 6|-grains of muriated filver.

e. The nitro-muriatic folution after beingconcentrated by evaporation, was poured into alarge quantity of water, upon which a whiteprecipitate fell down, weighing, when dried,133 grains. This was oxyd of antimony, en-tirely unmixed with the fmalleft portion ofarfenic. When fufed in a covered cruciblewith tartar, a button of reguline antimony wasproduced, and this when heated on a teft beforethe bellows, was volatilized, leaving behind 0.5grains of filver.

f. The refidues of the nitro-muriatic folution( e ) and of the nitric folution (c), were mixedtogether and diftilled till denfe white vapoursbegan to rife; this concentrated fluid was thendiluted with water, and muriated barytes wasadded as long as any decompofition took place.The fulphat of barytes thus obtained amountedto 194 grains.

In this analyfis the muriat of filver obtainedamounted to 399 grains, which, being reducedto the metallic ftate furnilhed, together with thehalf grain of filver contained in the antimony,exadtly 300 grains of pure filver, a refult whichwas confirmed by two allays of this ore on thecupel, each of which yielded 30 per cent, offilver.

In order to afcertain the quantity of antimonycontained in the 132 grains of white oxyd, 100grains of reguline antimony were digefted inwarm muriatic acid, to which nitric acid wasadded drop by drop, till the whole of the metalwas diffolved. This folution being concentratedby evaporation and then poured into water,afforded 130 grains of white oxyd. Hence theabove 132 grains indicate 101.5 of regulineantimony.

With refpetl to the fulphuric acid whichmade its appearance in this analyfis, it is affirmedby Klaproth to have pre-exifted, at leaft for themoft part, in the ore, and not to have been pro-duced by the adtion of the nitric acid upon thefulphur, for the following reafons. In the firftplace the quantity of nitrous gas difengagedduring the adtion of the nitric acid on the oreis by no means fufficient to account for the pro-duction of fo large a quantity of fulphuric acid.Secondly, fome finely pulverized red filver orebeing digefted with ftrong muriatic acid, thefolution was found to contain not only antimony

* Klap. Analyt, Eff. X. 117.