234 CALIFORNIA ALKALINE AND BOBACIG LAKES. 



Geysers and hot springs are numerous in the whole of this district, and 

 from the number of extinct geyser-vents still visible they" were probably, at 

 one time much more numerous than at present. 



The analysis of an average sample ot the boracic material from Nevada 

 afforded Mr, Loew the following results : 



Boronatrocalcite 22.13 



Chloride of sodium 2.80 



Sulphate of sodium 2.62 



Sulphate of calcium 6.17 



Carbonate of calcium 3.01 



Carbonate of Magnesium 79 



Clay 19 70 



Quartzose sand 26.03 



Water 15.04 



Traces of potash, iodine, and loss 1.71 



100.00* 



The purification of crude borax (tincal) is effected by a simple recrystal- 

 lization, but the preparation of marketable borax from boronatrocalcite is 

 attended with considerable difficulty, more particularly- as the appliances 

 available in the remote deserts in which it occurs are of the most primitive 

 and limited descrijjtion. 



When boronatrocalcite is moderately pure it is first ground and subse- 

 quently dissolved in water, with the addition of an amount of carbonate 

 of sodium sufficient to effect the decomposition of the calcic carbonate 

 present. 



The solution is subsequently heated, and the carbonate Of calcium al- 

 lowed to subside, when the liquor is drawn off, and, after concentration, borax 

 is obtained by crystallization. 



Unfortunately, this mineral often contains notable quantities of gypsum, 

 which transforms an equivalent amount of carbonate of sodium into Glau- 

 ber salt, a relatively valueless product. This salt is also frequently present 

 in the material operated upon, and thus materially adds to the difficulty 

 of treatment. In order to avoid these difficulties, it has been. proposed to 

 treat native boronatrocalcite with'sufficient sulj)huric acid to transform the 

 whole of the carbonate of calcium into gypsum, and to liberate boric acid 

 to be subsequently saturated by carbonate of sodium. Boronatrocalcite has 

 also been treated with excess of hydrochloric acid, in order to obtain crys- 

 tallized boric acid, but neither of these processes has hjtherto afforded satis- 

 factory commercial results. 



The comparatively recent discovery of large quantities of this substance 

 in Nevada will, no doubt, eventually, to some extent, affect the Tuscan pro- 

 ducers of boric acid; but the fact that crude boronatrocalcite varies consid- 

 erably in its composition, and that it is found in situations in which its 

 local treatment would be almost impossible, has hitherto prevented this 



* Moniteur Scientifique, 1 876, p. 1 ,230. . 



