SULPHATE OP IRON 953 



the Wood, is secreted from the skin with the sweat, and remains, generally in connec- 

 tion with this, attached to the wool. Chevreul discovered, some time ago, that this 

 peculiar mixture, known by the French as Suint, constitutes not less than one-third 

 the weight of the raw merino fleece, from which it is easily removed by immersion in 

 cold water. In ordinary wools the suint is less, the amount being about 15 per cent, 

 of the raw fleece. Formerly it was considered as a kind of soap, mainly for the 

 reason that the wool, besides this sometimes contained about 8 per cent, or a not 

 inconsiderable quantity of fat. This fat, however, is usually combined with earthy 

 matters, mostly with lime, and consequently forms a soap which is very insoluble. The 

 soluble suint is a natural salt (sudorate of potash) arising from the combination of 

 potash with a peculiar animal acid, of which little is known. Especial effort has 

 lately been directed to suint, in order to obtain as much as possible of the potash 

 eliminated from the animal, and a special industry has been established in various 

 portions of the great French wool district, such as Rheims, Elboauf, &c. 



A company purchases from the wool-raiser the solution of the suint obtained by 

 rinsing the wool in cold water, the price paid for it being higher in proportion as it is 

 more concentrated As a general thing it is maintained that a fleece weighing nine 

 pounds contains 20 ounces of suint, which should contain about one-third part, or six 

 to seven ounces of potash, although not more than five and one-half ounces, are per- 

 haps directly available. 



In the wool manufactories of the towns just referred to, there are nearly 60,000,000 

 pounds of wool washed annually, the yield of about 6,750,000 sheep. This quantity 

 should contain over 3,000,000 pounds of pure potash. Thus the water in which the 

 wool is washed, and which was formerly thrown away, is made to yield a product 

 adding appreciably to the value of the wool itself, and more than covering the cost of 

 its treatment. It is, of course, not an easy matter to utilise the solution of suint on a 

 large scale ; but, wherever the work is carried on by the wholesale, as it is in connec- 

 tion with all great manufacturing establishments, it will undoubtedly become a regular 

 part of the process of manufacture. 



SULPHATE OF ALUMIWA AND POTASSA is common alum. See ALUM. 



SULPHATE OP BARYTA is the mineral called Heavy-Spar. See BARYTA, 

 SULPHATE OF. 



SULPHATE OP COPPER, Rotnan or Blue Vitriol (Kupfervitriol, Ger.), 

 CuO.SO 3 (CuSO 4 ), is a salt, composed of sulphuric acid and oxide of copper, and 

 may be formed by boiling the concentrated acid upon the metal, in an iron pot. It is, 

 however, a natural product of many copper mines, from which it flows out in the 

 form of a blue water, being the result of the infiltration of water over copper pyrites, 

 which has become oxj'genated by long exposure to the air in subterranean excavations. 

 The liquid is concentrated by heat in copper vessels, and then set aside to crystallise. 

 The salt forms in oblique four-sided tables, of a fine blue colour ; has a spec, gravity 

 of 2'104 ; an acerb, disagreeable, metallic taste ; and, when swallowed, it causes violent 

 vomiting. It becomes of a pale dirty blue, and effloresces slightly, on long exposure 

 to the air ; when moderately heated, it loses 36 per cent, of water, and falls into a 

 whitish powder. It dissolves in 4 parts of water at 60, and in 2 of boiling water, 

 but not in alcohol ; the solution has an acid reaction upon litmus-paper. When 

 strongly ignited, the acid flies off, and the black oxide of copper remains. The con- 

 stituents of crystallised sulphate of copper are oxide, 31'80; acid, 32'14; and 

 water, 36'06. Its chief employment in this country is in dyeing, and for preparing 

 certain green pigments. (See SCHEELE'S and SCHWEINFURTH GREEN.) In France, 

 as well as in England, the farmers sprinkle a weak solution of it upon their grains 

 and seeds before sowing them, to prevent them being attacked by birds and insects. 

 See COPPER. 



SULPHATE OP IRON, Green vitriol, Copperas (Couperose verte, Fr. ; Eiscn- 

 vitriol, Schwcfelsaurcs Eisenoxydul, Ger.), FeO.SO 3 (FeSO 4 ), is a compound of sulphu- 

 ric acid and protoxide of iron ; hence called, by chemists, the protosulphate ; consisting 

 of 26'10 of protoxide of iron, 29'90 of sulphuric acid, and 44-00 of water, in 100 parts. 

 It may be prepared by dissolving iron to saturation in dilute sulphuric acid, evapo- 

 rating the solution till a pellicle forms upon its surface, and setting it aside to crystallise. 

 The. copperas of commerce is made in a much cheaper way, by stratifying the pyrites 

 found in the coal-measures ( Viiriolkies and Strahlkiesofihe Germans), upon a sloping 

 puddled platform of stone, leaving the sulphide exposed to the weather, till, by the 

 absorption of oxygen it effloresces ; lixiviating with water the supersulphate of iron 

 thus formed, saturating the excess of acid with plates of old iron, then evaporating and 

 crystallising. The other pyrites, which occurs often crystallised, called by the Germans 

 Sckwefelkics or Eiscnkies, must be deprived of a part of its sulphur by calcination 

 before it acquires the property of absorbing oxygon from the atmosphere, and thereby 

 passing from a bisulphide into a sulphate. Alum-schist very commonly contains 



