Page:Madras journal of literature and science vol 1 new series 1856-57.djvu/32

20 which I am but partially informed; these will chiefly embrace 1st, the present quantity available for the market: 2nd, constancy of the supply: 3rd, local demands for the salts, which can only be known to those residing near the lake: 4th, means of transit, should a demand exist or arise elsewhere: 5th, the small probability of bringing any natural carbonate from a distance to compete in Europe, with the carbonate of soda made from common salt by Leblanc's process: 6th, the want of any extensive Indian manufactories of glass or soap, for which in Europe alkaline carbonates are principally employed.

The foregoing observations apply more or less strongly to all the samples containing carbonate of soda. The sample No. 2, which is essentially a pure rock salt, deserves more consideration, as it might, supposing it to exist in quantity, be turned to account as a source of revenue; there being always, from the large consumption and high price of the article, a ready market for good common salt in India. Sample No. 7 is worth a trial for building purposes, provided that the common salt present could be eliminated by washing.

The purification of the salts Nos. 1, 3 and 4 is easily effected by simple solution in hot soft drinking water, decanting or syphoning off the supernatant clear fluid to separate insoluble impurities, and evaporating in cast iron or sheet iron pans by means of furnace heat. As to whether the purification would prove profitable or not will depend on the expense incurred for fuel and cooly hire, and the price of the evaporating pans, together with that of the purified article; the latter is a main point to be considered, and cannot be seen before hand.

No. 2 requires little or no purification.

No. 5 might be purified in the same manner as Nos. 1, 3 and 4. There will exist in solution, a mixture of common salt and carbonate of soda, the former averaging about 25 per cent.; by concentration of the solution, (which should also be effected in iron pans), the common salt, from its less solubility compared with the carbonate of soda, and its equal solubility in both hot and cold water,