Food for Xhe surface of the desert is covered with earth or rock, 



^^^"^^ called ■' costra," which varies from three to ten or more feet 



^ in thickness. Under this is found the " caliche," or crude 



Nitrate. The layer of "caliche " is sometimes eight or ten 



feet thick, but averages about three feet. This " caliche " 



contains on the average about 50 per cent of pure Nitrate 



of Soda. 



The " caliche " is refined by boiling in water to dissolve 



the Nitrate. The hot water is then run off and allowed to 



cool in tanks, when the Nitrate forms in crystals like com- 



mon salt. The Nitrate is then placed in bags of about 



three hundred pounds each and shipped to all parts of the 



world. Nitrate of Soda, as exported, contains about 15^ 



per cent of Nitrogen. The export of Nitrate of Soda from 



Chile, in the year 1890, amounted to over a million tons 



of 2,240 pounds each. By far the largest part of this went to 



Europe, for use as a fertilizer. How these beds of Nitrate 



were formed has been the subject of much speculation. 



The generally accepted theory is, that they were formed by 



the gradual decomposition and Nitrification of marine 



animal and vegetable matter, containing a considerable 



amount of Nitrogen. 



The same wise Providence that stored up the coal in 



the mountains of Pennsylvania to furnish fuel for the people 



of the United States when their supply of wood had become 



exhausted, preserved this vast quantity of Nitrate of Soda 



in the rainless region of Chile, to be used by the people of 



the nineteenth century to furnish their crops with the 



necessary Nitrogen, when the natural supply in the soil had 



become deficient. 



., ^ , Bv "complete fertilizers," we mean fertili- 



Complete ^ ^. . ^.j. u u • -j 



P ... ,, zers containmg Nitrogen, phosphoric acid 



^. j^ ' and potash. This includes the majority of 



c . the fertilizers sold. These fertilizers are 



bxpensive , n 1 .. 1 u . " d 1 



p, P . commonly called "phosphates. reople 



have fallen into the habit of calling any 



commercial fertilizer a "phosphate," whether it contains 



any phosphate or not. 



Bearing in mind that all that is of any value in these 



" phosphates," no matter how high sounding their names, 



is Nitrogen, phosphoric acid and potash, let us see what 



thev are really worth — that is, what the same amount of 



