118 THE NITRATE OF SODA. AND 



tubs ; bateas of iron or wood as crystallisers ; tubs for mother liquor ; 

 provisions for the people and food for animals. The salitero or refiner can 

 now commence operations, having, however, previously obtained legally his 

 estacas of 200 square yards. Some manage to become possessors of very 

 large tracts of nitrate grounds. 



The salitero now directs his barretero or quarryman to make openings 

 with a heavy iron bar, increasing in width at bottom, through the costra 

 and caliche to the coba ; this is the tasa or cup into which is put from one 

 to fifteen hundred weight of very rough powder (made from nitrate of soda, 

 and sulphur from the volcano of Isluga), the upper part being well rammed 

 with loose earth ; these are called bombones, and are exploded, which 

 loosens the earth and turns it up. The irregular masses of caliche are 

 broken into large lumps, collected out of the loose mass, and conveyed in 

 panniers by asses to the oficina or refinery ; here the large pieces are broken 

 into smaller by the asendrador and thrown into tbe boiler, to which, when 

 nearly full, water is added, and the boiling commences, more caliche being 

 added at intervals. In about seven or eight hours the saturated boiling 

 point of the liquid has attained a temperature of 240° F., when the mother 

 waters are added. The boiler-man now removes with a shovel the borra or 

 salt that has been precipitated, and earthy matters separated and subsided 

 to the bottom of the boiler. The solution is bucketed out into the deposito, 

 where a further quantity of earthy matter, the ripia, goes down, leaving a 

 clear solution, which is then run into coolers, where crystallisation takes 

 place, producing salitre or refined nitrate of soda, which is shovelled out of 

 the bateas, and the sun's heat soon dries it. It is now bagged and sent to 

 the coast for shipment. The best refined nitrate was found to be composed 

 of water, 0.11 ; salt, 1.84 ; sulphate of soda, 0.35 ; nitrate of soda, 

 97.70 = 100,00. This nitrate trade employs nearly all the people in the 

 province, about 12,000, exclusive of foreigners and Chinese labourers. The 

 exports could be increased to any extent, as the nitrate grounds are 

 inexhaustible. 



Messrs. George Smith & Co. have been using large boilers, and of more 

 scientific construction, with advantage ; they also have commenced boiling 

 by steam. The fuel used is the tamarugo and algarobo trees ; these are 

 getting very scarce ; thus much English and Chile coal is also resorted to. 



This nitrate of soda has been known about a century. It was discovered 

 by a woodcutter, named Negreros, in the Pampa de Tamarugal, by his 

 having made a fire at the spot that still preserves his name ; the ground 

 began to melt and run like a stream — the melted substance was examined 

 and found to be nitrate of soda. 



About 1794 the German mineralogist, Haenke, was sent to the province 

 to teach the method of its extraction, and turn it into nitrate of potash, for 

 gunpowder, which it is said he did, by adding to it a solution or ley pre- 

 pared from burnt cactus, which contains 8 per cent, of potash. Caliche 

 was subsequently sent to Concepcion, in Chile, to be turned into nitre, but 

 with little success. In my first series I have given some particulars as to 



