The Birmingham age-herald., 1914-09-13
BY FRANK c. CARPENTER

more than 70 feel below the surface of the desert
 As to whence these great fields of nitrate come there are mhny different theories. One is that this part of Chile was once the bed of an inland sea and that the nitrate came from the decay ing of the nitrogenous seaweed. An other theory is that the ammonia which arose from the vast beds of guano in the islands of the west coast was car ried by the winds to the mainland, where it condensed and united with the other chemicals of the soil to form the deposits. third supposition is that the nitrates came from certain electrical discharges of the Andes which combined with the air so as to make nitric acid, the acid being de- posted in these beds in the form of nitrate of soda.
 None of these theories is satisfactory, and yet the scientists have little better to offer. Dr. Walter S. Tower of the Chi cago university says they have come from a great lagoon which was formed in this region by the rising of the land in such a way that it formed the home of s world of bird life. The lagoon was shallow and the birds waded through it and fed on its shores. Their droppipgs formed guano. and as evaporation went on this combined with other chemicals in the water and soil and the result was nitrate of soda. At any rate, the nitrates have been pre- served by the dryness of the desert, which Mas no moisture to leach them out of the soil.
 I wish I could take you out into the country and show you how these great deposits of valuable fertilizer are taken cut of the earth. Where the mining is done the land looks as though 1t had been plowed up by giants. The earth lies in mammoth clods of all shapes and sizes, and beyond are nothing but bleak and bare sand. There is no sign of vegetation nor life of any kind. All is sand and salt rock. The rock is of different colors, ip some places white and in others yell low, gray lemon colored or green. The nitrate lies in beds or strata at some dis tance under the surface; and the method of getting 1t out is to bore round hole a foot in diameter through the layers of sand and rock above 1t and blow it out with blasting powder. The powder is made on the spot and that out of nitrate similar to that which it is to blow up. The only things required in addition are charcoal and sulphur. The explosion breaks up the earth for a radius of 40 feet around the charge, and the charges are put in in rows so that the mining can be done in trenches. After the rock has been broken. it is dug up with picks and crowbars. It is broken up into Jumps of such size that they can be loaded upon the cars and be taken to the factories where it is further reduced by machinery made for the purpose.
 Nitrate is seldom found pure in nature As it lies in the desert it is mixed with other rock, and the best of the deposits contain only from 40 to 60 per cent of
 
 more than 20 per cent it is called calche. and if less than that it is eostra. The costra lies on the top and the calche is usually found underneath. Before the stuff can be used it must be refined and all the earth and rock taken out. The laws require that the salts exported must be 8 per cent or more pure. It is such salts that form the nitrate of soda of commerce.
 There have been but few changes in the methods of nitrate reduction since 1