Nitrate of soda is seldom found pure, and the nitrate rock, called caliche, will vary from ten to sixty per cent. of the pure mineral. In some fields it is found on the top of the soil, and in others it is as much as forty feet beneath the surface, with the strata of salt rock on the top of it. It varies considerably in composition. Holes are dug or drilled down through the caliche until a bed of gravelly material is reached, into which charges of dynamite or blasting powder are placed, and the nitrate rock is thus loosened up. When first exposed the nitrate is sometimes as soft as cheese, but it hardens on contact with the air. The lumps thus broken are then dug out with picks or crowbars and hauled in mule-carts to the oficinas.
There are many of these mills throughout the nitrate fields, and they are busy places. The lumps are first crushed, and are then lifted by elevators and placed in huge tanks filled with sea water. These tanks are encircled by coils of steam pipes, which heat the water that is poured in with the rock to any desired temperature. Nitrate is soluble in water, and this purifying process rests upon the fact of its greater solubility in water heated to the boiling point, than the other salts with which it is associated. When the water has become supersaturated in the boiling tanks, the nitrate of soda in solution is drawn into shallow vats which are exposed to the air. At this state it looks like pale maple molasses. As it cools, the nitrate of soda crystallizes in the vats, together with a little common salt and a small amount of other impurities, and the sides become covered with white sparkling crystals like alabaster. These crystals are then shovelled upon drying boards and exposed to the sun for a time, after which they are graded and put into bags weighing a little over a hundred pounds each. This product, which is ninety-six per cent. chemically pure nitrate of soda, is then transported to the seacoast, from whence it is shipped to Europe or the United States, the latter country receiving about one-fifth of the whole.
Another product of these nitrate beds is iodine, which remains in the liquid after the removal of the nitrate. This liquid is poured into smaller pans, and is chemically treated until the iodine is precipitated in the form of a black powder. This is then heated in a retort which changes it to a vapour, and it is again condensed into beautiful violet crystals. The iodine is packed in small casks which are shipped with bullion and other valuables, for each cask is worth several hundred dollars. As the consumption of iodine is not very large the oficinas refine only a part of the iodine in order to keep up the price.
More than two million tons of nitrate of soda were shipped from Chile last year, which is the greatest amount that has ever been produced. It has been found especially valuable for increasing the growth of the sugar beets in Europe, as it seems to provide the soil with the essential elements for their growth. The consumption in the United States is increasing rapidly, and it is looked upon as the best fertilizer provided by nature. According to horticultural authorities it has been found especially efficacious in stimulating the growth of vegetables, such as cabbages, onions, carrots, beets, etc., and for field crops of many kinds. It is said that even the Incas of Peru were acquainted with its value as a fertilizer. It is also extensively used in the manufacture of gunpowders and other high explosives, which in itself makes a considerable demand.
The discovery of the value of nitrate as a fertilizer was by accident. A poor Scotchman, who lived near where Iquique now stands, had a small garden which he cultivated with great care. One day he noticed that a part of his garden, which had been banked up with soil containing this mysterious white substance, flourished much more than the rest. This led to experiments and some of this soil was sent back to Scotland. The success of the experiments that followed gradually led to the development of the present industry, but the discoverer died as poor as he was born. The first nitrate works were established at Noria in 1826. It was not until after the war between Chile and Peru that the industry reached great proportions. Then an Englishman by the name of North began its development and soon afterwards became known as the “nitrate king.” Other nitrate princes rose, and thrived like the bonanza mining kings of Mexico and Peru in their best days. Englishmen became peers of that country through the influence of colossal fortunes paved with saltpetre. In its raw state the nitrate contains some properties injurious to plant life, but these are removed. As this process requires the latest modern machinery to do the work economically, the business has drifted into the hands of big combinations of capital.
As the government of Chile exacts an export tax on every sack of nitrate of soda exported, the revenue from this source is enormous and pays more than two-thirds of the expenses of that extravagant government. Chile owns practically all the nitrate of soda in the world. Small quantities have been found elsewhere, but in this region are the only deposits that can be operated at a profit. Most of the nitrate fields at one time belonged to Peru, but Chile appropriated them as indemnity, after a disastrous war was waged between the two countries in 1880, in which Chile was victorious. You can not meet a Peruvian anywhere to-day who does not swear vengeance against Chile, for thus robbing his country of her greatest source of wealth.
LOADING NITRATE.
English capital has developed this great industry in Chile, and no less than one hundred million dollars in British sovereigns have been invested in these dreary wastes. Almost one hundred million dollars’ worth of this salitre has been exported in a single year. The ports are at all times filled with vessels which have brought coal and merchandise, and are awaiting a load of nitrate. It is seldom that the Stars and Stripes are seen floating from a masthead, but it is a welcome sight to an American. The profits for a few years were so great that an overdevelopment followed, and the price greatly dropped. Then a trust agreement was, arrived at limiting the output, but even that was not a success and the production is again unlimited. The population of the nitrate district is a cosmopolitan one, and represents almost every nation on the face of the earth. It gives employment to many thousands of persons. A homesick and stranded American is not an uncommon sight.
It is estimated that at the present rate of mining the known fields of nitrate of soda in Chile will be exhausted in fifty years, or less. The official board of engineers has recently reported to the Chilean government that there are in sight four and a half million quintals (220.4 lbs.) of nitrate in the deposits of the country. A previous estimate had fixed the visible quantity at less than half that amount. It is doubtful whether either of those estimates is very reliable. At any rate the government and owners of the oficinas are pushing the sales in every way, and exploiting the use and value of nitrate as though it was inexhaustible. It is possible that similar deposits may be found on the Sahara Desert, or some of our own desert lands where similar climatic and atmospheric conditions exist. The value of nitrate lands in Chile has risen rapidly in recent years, and nearly all the undeveloped fields are now owned by the Chilean government, which auctions them off as the need for money arises.