At Itebas, in Catalonia, arsenic is obtained as a bye-product from the smelting of ores contain ing small quantities of mispickel, by passing the gaseous products through a series of flues connected with the smelting furnace. The process is carried on in much the same manner as in Cornwall and Devon, except that the furnace is somewhat different in construction. It is made so as to allow the flame to enter the furnace, and to play upon the charge in the interior, being shut off by means of a damper when required. The furnace bed is supported upon cross-walls of brick work, through which the flame is allowed to pass when the damper is open ; when it is closed, the flame passes through a flue into the chimney. There is another damper, also, which is closed when the flame is reqnired inside the furnace, in which case the products of combustion sre conducted away through a second flue. The process of refining or re-sublimation is precisely the same in Spain as that employed in Saxony a.nd Arsenic is extensively used in the manufacture of the sulphides, orpiment, and renlgar, and of various pigments, sueli as arsenite of copper, or Scheele's green, Seluseinfurth green, and others, In glass-tnaking, it is employed to combine with the iron contained in the sand, and thus to prevent it from imparting an objectionable tinge to the glass ; it also enhances the lustre and brilliancy of the better kinds of glass. Dyeing nnd calico-printing consume large quantities of arsenic, and it has lately received a new application in the manufncture of aniline dyes. Owing to the power possessed by arsenic of arresting putrefaction, it is employed by naturalists in the fonn of a soap for the preservation of stuffed birds and other organic speeirnens. In agriculture, it is used in solution as an anti-srnut for seed wheat, and as an anti-vermin lotion for eheep and cattle, but its use is not free from danger, especially to the shepherds or dippers. In Spain and Germany, it is largely used in the preparation of fly-poison, vermin-killers, &c. Taken in minute doses, it ia much valued as a powerful hotnceopathic remedy.
The quality of commercial arsenic depends upon its purity. Thc best quality is perfectly white, but the presence of sulphur, due to its deposition with the arsenic in the condensing flues or chambers, imparts to the latter a highly objectionnble yellow tinge. This is especially character istic of the German article, which is often called " yellow arsenic." The arsenic frUal SWUINICE1 is also yellowish in colour, while that from the works in Cornwall and Devon is entirely free from sulphur. Refilled arsenic should be in compact, v.treous lumps, and perfectly free flora particles of metallic arsenic ; when of bad quality, it is in loose masses, more or less soft and friable, due to re-subliming the crude acid under too feeble a temperature.
The nianufacture of arsenious acid is carried on chiefly in the neighbourhoods where the mines containing arsenical ores aro worked. Although arsenic is almost ns widely distributed as any known metal, yet, with one or two exceptions, it is found only in such minute quantities as to be worthless for the purpose of extraction. Consequently the seats of this industry nre few in number.
In England, the most important works are scattered about in Cornwall and Devon. There are ono or two also situated in the neighbourhood of Swansea, in Glittnorganshire. The arsenic districts on the Continent are Altenberg and Freiberg, in Saxony ; Reichenstein, in Silesia; and the province of Catalonia, in Spahr. The works at Altenberg and Iteielienstein are supplied hy two mines of arsenicn1 pyrites in Silesia.
Arsenic has been manufactured in small quantities for a large nutuber of yrars, but during the last twenty years it has undergone very considerable development. Although the production is confined to a small number of works—there being only about ten manufacturers in this country— these works have been extended from time to time in order to meet the rapidly increasing deniand. The amount of capital needed to carry on the naanufacturo depends upon the manner in which the arsenic is obtained. If the arsenical ores are treated directly for this article, the plant required may consist of an ordinary reverberatory furnace, with flues and chimney of greater or less length ; but if the arsenic be obtained as a bye-product from the smelting of tin or copper ores, the only extra cost lies in the erection of flues and chambers in connection w ith the calciner. In either ease, another reverberatory furnace mad set of condensing chambers are requimd for the re-subliming operations. The most expensive item in the erection of the flues is the slate with which they sre occasionally lined.
The price of arsenio is constantly varying, between the limits of 71. and 151. per ton. It is ruled to a great extent hy " rings," which consist almost entirely of merchants. This is illustrated by the course of prices during the first six months of the year 1878. A combination of merchants drove up the price from 71. to 121. in three weeks, all surplus stocks being got rid of by consig,nment to the United States. The combination, however, broke down, and the price of arsenic fell, almost as rapidly as it had previously risen, to 81. per ton. Such manipulations are readily carried through, because the make is small—ouly about 8000 tons per annum, and, as pointe,d mat above, in very few hands (see Acids).
Orpiment. (Fn., Orpiment; GER., Auripigment.) Formula, As2S3.—Orpiment, or trisulphide of arsenic, is a lemon or orange-yellow coloured substance, found native in Hungary, the Hartz, and other places; the finest samples used by artists (golden orpiment) come from Persia. The commercial article is artificially prepared for use as a pigment in the following way:— A mixture of arsenious acid and sulphur is pined in an iron sublituing-pot, similar to those used in the preparation of crude white arsenic. The mixture is then heated until the sublimate which immediately forms upon the rings fixed above the pot begins to melt. The proportions of the two ingredients used. vary largely; the best colours being probably produced when the mixture contains from one-third to one-fifth of sulphur; for the lighter colours, a smaller proportion of sulphur is employed. Orpiment made in this manner consists of a mechanical mixture of sulphide and oxide of arsenic.