twenty thousand pounds of well-rotted stable manure. The experts say that, while manure is of unquestionable value, the quantity of it required to produce good results may be greatly reduced by the use of chemical fer

tilizers.

Under these conditions only enough of it need be employed to give lightness and add humus.

The so-called "complete" fertilizers, so widely advertised, are, as a rule, not economical to buy. In other words, they cost the farmer more than they

are worth. They are generally incomplete, containing as they do an insufficient percentage of nitrogen. To make certain of results the farmer ought to purchase his fertilizing materials separately, and mix them for himself. An inquiry addressed to his State agricultural experiment station will elicit a prompt reply, telling him how, and giving the proper proportions.

Some lands need lime; others demand. phosphoric acid or potash. Soils differ in their requirements. But in these days the farmer can get exact information about the needs of his own particular soil by sending a sample of it to the nearest experiment station. The Department of Agriculture is giving very important help in this work by extensive soil surveys and by the publication of soil maps.

Nitrogen in the form of nitrate of soda can be bought for the same price per pound as in any other form. Ordinarily, the market price is eighteen cents a pound. But much lower prices are obtainable by purchasing the stuff in carload lots a carload being not less than

ten tons. If the farmer does not want so much for himself, he can get his neighbors to go shares with him, thus saving a good deal of money. A point worth mentioning in this connection is that the

dealer (usually located in a seacoast town) should be instructed to ship the nitrate as "fertilizer." Otherwise much higher freight rate may be charged on the shipment, as "chemical." When nitrate of soda is used without other fertilizers, not more than one hundred pounds to the acre ought to be employed.

The best way to use the nitrate is to mix it with its own weight of

dry loam immediately before applying it. It comes in lumpy form, and should be broken fine by turning it out on the barn floor and smashing the crystals with the back of a spade. When it has been run through a sieve with a mesh not larger than one-fourth of an inch, it is ready to be put on the land.

Mixed with the loam, it may be applied by sowing it broadcast, or by any fertilizer-distributing machine. If merely distributed on the surface, it will be quickly absorbed by the soil; or it may be cultivated into the soil with a harrow or cultivator. The capillary movement of the soil waters will do the rest. It is desirable not to use the nitrate in excessive quantities too close to the plants, and in no case should wet foliage be sprinkled with the dry chemical.

Other familiar sources of nitrogen are fish, cottonseed meal, dried blood, and the

comes from deposits in the northernmost. province of Chile, where they extend in a narrow strip some hundreds of miles in length through a region of rainless. desert between the coast range and the Andes. These deposits are not on the surface, but hidden beneath a rocky crust some feet thick. The method adopted in mining the material is to bore a hole and lower into it a boy who digs a sort of burrow in the clay that lies beneath the layer of nitrate. A blast is then introduced, and the nitrate is blown upward and through the surface crust. It is more or less mixed with other substances, being from seventeen to fifty per cent pure. To refine it, the material is crushed and boiled in huge tanks, and the hot water containing the nitrate in solution is then run off and allowed to cool in shallow pans. The precious chemical, crystallizing out as a greyish or yellowish salt, is finally packed in bags for export.

waste of slaughter houses. None of these, however, furnishes the indispensable element in a form in which it can be taken up by plants. In such shape, it must first be converted into nitrate, so that it is only slowly available, and must be applied in the fall in order to be decomposed and utilizable by the crop in the following spring.

Compare the difference in productivity between European and American lands in wheat and oats-a difference that is based largely on the proper use of fertilizers: U. S. Eng. Germ'y. 14 bu.. 33 bu. 28 bu. .30 bu. 45 bu. 48 bu. Exhausted soils are no longer a terror to European agriculture. There are no "abandoned farms." Rational use of fertilizers has solved the whole problem.

Wheat Oats

It is supposed that the deposits represent the decomposed remains of seaweeds accumulated in vast quantities in a narrow arm of the sea, and later elevated through geologic causes to more than half a mile above the level of the ocean. Traces of actual seaweeds are found in them, and they contain much iodine (a conspicuous constituent of such marine plants), which is derived as a by-product from the "mother liquor" of the commercial nitrate.

It is estimated that there is enough nitrate left in these deposits to supply the world for three more centuries for such purposes as it can now be used. Were it to be universally applied to the soil of this country where needed, the in

G

REAT crystals of kunzite, the new lilac-colored stone which was discovered but a few years ago, will be dug from the miniature mine which has been erected on the grounds of the San Diego Exposition. The little replica will be complete, and although the gems have been "planted," the visitor will have the opportunity of seeing, in detail, how this remarkable mine is worked.

The original of the mine was discovered a few years ago in the Pala Mountains, forty miles from San Diego, and the stone was identified as a new variety by our greatest expert in precious stones. Remarkable tourmalines and great quantities of lithia minerals were found in the same deposit and the largest mine of its kind in the world was soon in full blast. The deeper in the earth the crystals of kunzite are found the

darker they are, so that all shades from the palest to the deepest lilac are found. The largest crystals are as large as a man's hand and weigh as much as one hundred and fifty carats.

The first crystal of kunzite that was found was bought by a New York millionaire for five thousand dollars and today most of the product goes to a big manufacturing jeweler of that city. Before it is cut it is valued at about fifty dollars an ounce and when set, at from six to twenty dollars a carat. Fairly large stones have the peculiar property of becoming phosphorescent when placed under the influence of electric current and give out a strong orange light, which is very different from their ordinary color. After the current is turned off the light continues for about three-quarters of an hour and it is possible to take a direct-contact photograph with the stone as with radium or the X-ray. No other stone of the same classification has this property.

Kunzite is found at an elevation of about twelve hundred feet in veins of granite rock. Following these into the earth at an angle of fifteen degrees, the miner finds pockets eight inches across.

GEMS FROM CALIFORNIA MINES A replica of a gem mine has been built for the San Diego Exposition.