ALKALIS 



SODA ALKALIS AND ALKALINE EARTHS 



Sodium Carbonate 



In Garhwal hemp-fibre is boiled before being bleached (see C'nntmiiis wnf ;<<<. 

 Fibre, p. 255). In India it would be almost impossible to over-estimate the 

 extent to which a crude carbonate of potash is employed. A better selection 

 of plants or improvements in the methods pursued for the production of pearl- 

 ash are subjects, therefore, of no small importance. It may accordingly bo 

 remarked that it is surprising that while immense tracts of mountainous land 

 are in India injuriously covered with various species of wormwood (.4r*ei*). 

 except as a manure used locally the ashes of these plants are not apparently 

 utilised by the people. From the high percentage of carbonate of potash which 

 A Useful New they contain, the preparation of pearl-ash from wormwood might be con- 

 Industry, fidently recommended to the poorer inhabitants of the temperate regions of 

 India as a useful new industry. 



In Bombay, especially in the rainy tracts, the system prevails of robing (as 

 it is called) the seed-beds. This consists in burying brushwood, boughs of trees, 

 cow-dung, etc., under a thin layer of soil, then firing the mass. In this way the 

 soil becomes highly charged with wood-ashes, the most important constituent of 

 which is doubtless potash. It is found that the finer qualities of rice can alone 

 be grown when the seed has been previously germinated on raft-beds, and later 

 on transplanted to the fields. It would be well, in connection with the subject 

 of potash as a manure, for the reader to consult Leather's admirable papers on 

 Indian Manures. [Cf. Agri. Ledg., 1897, No. 8; also Indian Soils, 1898, No. 2; 

 Mollison, Textbook Ind. Agri., i., 83-5, 119-21.] 



3. Potassium nitrate (see Saltpetre, pp. 972-5). 



D.E.P., 4. Sodium and its Compounds, Carbonate of Soda ; Ball, 



ii., 154. Man. Econ. Geol Ind., 1881, 492-7 ; Holland, Rec. Geol. Surv. Ind., i., 

 115. The term soda, strictly speaking, denotes the oxides of the metal, 

 but it is also used for the hydroxide and the carbonate. The last 

 mentioned is not only the most important commercially, but it is the 

 compound from which the majority of the other soda salts are made 

 or can be made, and therefore it may be dealt with in greatest detail. 



CARBONATE OF SODA is a valuable salt ; it exists in nature and is, as a rule, the 

 most abundant and, from the point of view of the agriculturist, the most ob- 

 jectionable ingredient of the soluble sodium salts found in the soil. This subject 

 will be dealt with in a further paragraph under the heading of Reh deposits (see 

 below). It may be here observed that from such deposits carbonate of soda can be 

 isolated and purified commercially, or a crude mixed salt can be made that might 

 be utilised in the manufacture of special alkalis or in the glass, soap and other 

 trades. Sodium carbonate in an even purer state may be obtained from the 

 brine of certain lakes, such as the Lonar in Berar. 



Kelp and Manufacture from Kelp. In Europe some few years ago a large trade used 



Barilla. to exist in the separation of sodium carbonate from calcined sea-weeds KELP, 



or salt-worts BARILLA. Indeed to this day it may be said that SALSOLA SODA 



is still regularly produced both in France and Spain because of the large amount 



and fine quality of soda obtained from its ashes. And it was the loss of their 



regular supplies of barilla, during the wars with Spain, that compelled the French 



Origin of people to seek for new sources of the salt and finally led to Le Blanc taking out 



Le Blano a patent in 1792 for the artificial manufacture of carbonate of soda from common 



salt. Le Blanc's discoveries practically revolutionised the chemical works and 



industries of Europe (see pp. 50-1). The calcination of sea- weeds is pursued as 



a rule for the purpose of obtaining potash rather than soda, and at the present 



Iodine. day " kelp " is much more frequently spoken of as the source of IODINE than of 



either of the alkalis named. [For particulars regarding the manufacture from 



Sea Salt the reader might consult Agri. Ledg., 1902, No. 5.] 



One of the greatest economies in the carbonate of soda industry was effected 

 Sulphuric Acid. by the manufacture of SULPHURIC ACID from PYRITES, in place of from the ex- 

 Copper Pyrites, pensive Sicilian SULPHUR. The extensive deposits of copper pyrites that exist 

 Sulphur. in India, if utilised in the combined production of copper and sulphuric acid, 



Prospects. should open a highly lucrative field of enterprise. So also the manufacture of the 



phosphatic deposits of India and adjacent countries into superphosphates should 

 not be neglected, though so far as at present known the phosphatic deposits of 

 India seem to contain too much iron and alumina to make really good super- 

 phosphates. As an exemplification of such results it may be remarked that the 

 production of sulphuric acid from iron pyrites was in Germany 358,149 tons in 



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