The cost of the manufacture, as above described, is estimated to be as follows :— s. d.
231 lb. (105 kilos.) Stassfurtite (about 45s. 10d. per cwt.) .. 4 14 6 Carriage, grinding, and loss .. 1 6 330 lb. (150 kilos.) hydrochloric acid (about 3s. 5d. per cwt.) .. 10 0 Coal, labour, and wear and tear .. .. • • .. .. 5 0 £5 11 0 Yielding :— £ s. d.
176 lb. (80 kilos.) boracic acid (about 91s. 8d. per cwt.) .. 7 4 0 330 lb. (150 kilos.) chloride magnesium (about ls. 4d. per cwt.) .. 3 11 £7 7 11 giving a profit of 36s. 11d. It is probable that a greater yield of boracic acid would be obtained in practice.
The following attempt was made to manufacture borax direct from Stassfurtite. About 231 lb. (105 kilos.) of tbe commercial mineral were treated as in the first stage of the process for extracting boracic acid. The washing out of the foreign salts was performed in a cast-iron retort, walled in after the manner of the leaden pan before mentioned. The direct play of the fire on the retort must be avoided, otherwise it is impossible to prevent the powdered mineral from burning on to the bottom. After the lye was run off, through an opening at the bottom of the retort fitted with a strainer, the hole was reclosed, and over the paste was poured 660 lb. (300 kilos.) of crude eatistic soda lye of sp. gr. 1.33. The whole was thoroughly mixed with a wooden spatula, and heated up. It was necessary to stir up the mixture from time to time, to ensure the complete decomposition of the mineral. After an hour, about 44 gallons (200 litres) of water were added, the mass was mixed, and allowed to boil off again, and the fire was then withdrawn, or rather, allowed gradually to die out.
As regards the density of the solution : for making prismatic borax, it should be about 20°-22° B• (1 -161-1.180 sp. gr.) at 27° (80° F.) ; for octahedral borax, 1.263 sp. gr. at 76° (169° F.), the addition of more alkali to the solution being necessary. For this purpose, soda will do equally well. The contents of the retorts are allowed to settle for three to four hours, whereupon the liquid is removed, either through an opening iu the top, or by means of a siphon. It is then poured through felt into iron (or lead-lined wooden) crystallizing vessels. The lye remains for eight to fourteen days in these ; it is then drawn off, and again evaporated. The crystals of borax finally obtained are almost chemically pure.
The remaining sediment is collected, and treated in bulk with hot water, the lye is run off after the powder has settled, and fresh water is again applied. The united liquors are evaporated. The then remaining sediment contains hardly any borax. ln making borax direct, much more attention has to be paid to the conduct of the operation than is the case with extracting the boracic acid.
The value of the 202 lb. (92 kilos.) borax (say 6/. 9s.), and of the magnesite produced is more than a third less than the above estimated cost. In order to derive any profit from the manufacture, it would be necessary, if possible, to reduce the consumption of caustic soda lye to the equivalent (say 110-150 kilos ), and it may be more economically manufactured than purchased. Efforts may be made, too, ln the direction of replacing the caustic soda lye entirely or partially by carbonate of soda.
Among the minor occurrencea of boracic acid or minerals in Europe, which are not the subject of commercial undertakings, may be mentioned boracite at Liineberg in Hanover, and at Halber stadt in Transylvania. The acid, either free or combined, is present in a great number of mineral waters, though not in sufficient abundance to be a source of manufacture; allusion may especially be made to Vichy, Carlsbad, and Faxhingen (Nassau). During a long stay in Iceland, one of the most volcanic islands in the world, the writer made particular search for borax, analyzing some scores of samples of water from the mineral springs and boiling mud wells which characterize it ; but the results were singularly disappointing and contrary to expectation.
2. Asia.—Borax (borate of soda) hag been imported from Asia, from the earliest timea, under one of its local names, tinkcil. Before the utilization of the Tuscan boracic acid, no other source than Asia was known, and even the now familiar word borax is of Arabic origin. The modern discoveries of boracio compounds in less inaccessible parts of the world have done much to cripple the growth of the Asiatic product ; but we still import considerable quantities from our Indian Empire. By
many authorities, the salt is stated as an Indian product; this is not the case, it is entirely of trans-Himalayan origin. Stretching from Leh eastwards aloug the course of the Sutlej and the Brahmaputra, is a line of lakes, about a thousand miles in length, more or less explored. Many of these lakes are aalt in a marked degree, have no outlet, lie at a high altitude, and are fed in a great mesaure by subterranean infiltration. Thoae situated in Ladak and Great Thibet, are the sowrce of the ao-called " East Indian tincal." The most westerly deposits are those found in the uninhabited lake-plain of Pugha, in the former country. It lies at an elevation of over 15,000 ft. above the sea, on the Rulangchu, a small stream full of hot springa, joining the Indus on its left bank. The portion of the valley where the tincal is found may be roughly atated at 2 miles in length by mile in breadth, and, if not watered by, it is at least under the influence of, hot springs, whose temperaturea in four places vary from 51° to 75° c130°-167° F.), while the temperature of the stream fed by them reaches 13° (56° F.) in July. A aulphur mine exists on the haulm of the dream, and numbers of coarse garnets are found in the neighbourhood. The deposit of impure borax, locally known as soliaga, has a thick ness of several feet. It does not effloresce on the surface of the soil, as haa aometimes been said ; nevertheless a aaline efflorescence, composed principally of aulphato and aeaqui-carbonate of soda, with more or leas chloride of sodium, always indicates the existence of the subjacent beda of borax. The natives exhibit considerable skill in removing the valueleas efflorescence and collecting the borax beneath, employing a kind of wooden spoon or apatula. The gathering of the naineral cannot be carried on at all times ; on the contrary, each crop, as it may he termed, is dependent upon a catalytic action resulting from wet and subsequent evaporation, and having the effect of separating the borax from its impuritiea. The borax appears as a greasy aubstance, in a confused crystalline mass, of yellowiah-green to dirty-white or grey colour, and is divided by the natives into three qualities. These, according to aomewhat untrustworthy evidence, have about the following composition :—No. 1. Pure borax, from 68 to 85 per cent. ; chloride of sodium, 4 to 5 per cent.; aulphate of aoda, traces to 6 per cent. No. 2. Pure borax, 50 to 72 per cent.; chloride of sodium, 5 to 6 per cent. ; sulphates of aoda and lime, 10 to 20 per cent. This latter is in a powdery form. These two qualities are said to be generally mixed together, so as to yield an average of 70 to 72 per cent. of borax. The third quality is too impure for removal, and is left at the surface to cleanse itself by the natural process already mentioned. As artificial flooding has never been resorted to, the harvesting operation must be postponed till the occurrence of a natural downfall, which, at this elevation, usually takes the form of snow. The moisture sinks into the earth, taking up the impurities in ita passage, as they are much more soluble than the borax. Under the influence of the suu, the soil dries up again, and the dissolved salts effloresce on the surface, while the borax, thus naturally (partially) purified, remains below. About ten or twelve days are allowed to elapse, after the downfall ceases, before the gathering of the crop is commenced. During the hot months of July aud Auguat, the production could probably be much increased or hastened by artificially flooding the ground. Frost causes a total suspension of operations for a great part of the year. The depth to which the borax-yielding earths extend has never been ascertained ; but there is no doubt that they must exist in enormoua, probably inexhaustible, quantities. The thickness of each crop of borax does not exceed about 2 or 3 in., the effect of the catalytic action being limited to that depth ; the lower portion of the deposit, which is still impure, is exposed to the surface by the removal of each crop. The quality of the borax earth ia roughly judged by its hardness and weight. One man can collect a maund (about 80 lb.) in a day ; it is filled into little woollen bags, holding about 25 to 30 lb. each.