more quickly than vegetable matter, but this is now doubted. Tankage should be applied broadcast in the spring and harrowed in. Tankage and all animal fertilizers give the best results when used with manure, for the latter is rich in organic matter while meat is deficient in it.

Dried Blood.-A better article than tankage, because of its more uniform analysis, is dried blood. There are several grades of blood, since it is often mixed with tankage, when it is called blood and meat, but in the wholesale fertilizer trade, there are but two grades, the soft red blood and black blood. Both of these products. arise from the coagulation of liquid blood by steam. Under this heat the solid portion settles and the liquid is drawn off. The residue is then dried. If too much heat is used in drying, the blood solidifies into a solid black mass, hard and brittle. This, when ground, separates into small, black, glittering particles, having a gritty feeling, and constitutes the black blood of commerce. A lesser application of heat prevents the melting of the blood, and it comes out as a red powder, soft to the touch. It is difficult to dry this blood successfully, and dried meat or tankage is frequently added to facilitate the drying, which makes the blood and meat so generally sold, and which more properly should be classed as tankage.

Black and red blood differ materially in their action. The latter has acquired quite an insoluble condition that detracts from its agricultural value. It runs from twelve and one-half to fourteen and one-half per cent of nitrogen. Red blood contains less, only about ten per cent or eleven per cent of nitrogen, but it is a beautiful nitrogen preparation and admirably suited for fertilizing purposes, being soluble, while not too much so. It is, undoubtedly, the best animal ammoniate. Unfortunately, however, it rarely gets into farmers' hands, for

fertilizer manufacturers appreciate its value and take all that is produced. It is sold in the trade by the unit of ammonia. A unit is one per cent. When ammonia is worth $2.75 per unit, the price of blood analyzing 12 per cent ammonia is 12 times $2.75, or $33 per ton.

Dried Fish.-The leading animal ammoniate, the one most largely used by both manufacturers and farmers, is dried fish. This is obtained in very large quantities from the menhaden oil factories along the Atlantic coast. The menhaden, or "porgies" are caught for oil. They are steamed in large vats until reduced to a churn, and when this is settled the oil and water is drawn off and the churn is heavily pressed, to express all remaining oil. It is then called wet scrap and contains about 50 per cent of water. This is then dried, generally by the sun, the result being dry scrap. This contains about 10 or 12 per cent of water and from 8 to 9 per cent of nitrogen, or about 10 per cent of ammonia. It also contains about 8 per cent of phosphoric acid. The percentage of nitrogen varies according to the quantity of water contained in the scrap, which is sometimes quite large, even as much as 20 per cent in dry scrap. This variation is caused by defective drying, the effectiveness of which is largely governed by the weather. In some cases scrap is dried artificially, but this is not very general.

Dry scrap is sifted to make it uniform, and the result is a light, dry powder, having flaky particles. The finest dust is called fish guano. This runs some. what higher in nitrogen and is more valuable, because its fine mechanical condition renders decomposition in the soil very easy. Fish is classed under four heads, wet scrap, dry scrap, fish guano and ground fish; the distinction between the last two being slight and difficult to determine. The supply of scrap varies from year to year, according to the quantities caught; some

seasons the fish are very plenty, while in others they are scarce. In recent years, manufacturers have become rather more independent of the fish catch, owing to the increased consumption of nitrate of soda. While menhaden is by far the leading source of fish scrap, there are some fish preparations from the cod fisheries and from the sardine or herring fisheries. The supply from these sources is comparatively small, and they are not so well prepared for fertilizing purposes. Pure dry fish scrap is an excellent source of nitrogen. Its best results are obtained on rather light land, as the more compact nature of heavy soils, together with the larger quantity of water contained in such, apparently retards the disintegration of the scrap. It should

FIG. 18. a SHOWS A METHOD OF FIXING THE CLOTH SO IT WILL LAST FOR YEARS; b, ITS APPLICATION TO THE PLANT BED.

not be used in the hill, but broadcast only. It is less to be desired than dried blood, but it is far more easily obtained in the market, and it gives excellent results. Care should be taken to distribute it evenly, for if it accumulates in spots, an excessive fermentation results that is distributed to growing plants. Six hundred pounds of scrap can be used in place of 1,000 pounds of cottonseed meal, or 1250 pounds of castor pomace. As

in the case of tankage, it is best when applied with manure, because of its lack of organic matter. It need not be applied in the fall, for if broadcasted and harrowed in when the ground is being prepared in the early spring, it will become available for the crop by the time the plants are set.

Other Nitrogenous Substances.-In addition to these flesh preparations, there are others known as azontine, ammonite, etc. These are simply preparations of dried meat, but are of higher grade than tankage and are more uniform in composition. They can be classified with dried blood and similarly handled.

NITROGEN SALTS.

Beside the organic nitrogen supplies, both animal and vegetable, described in the previous pages, an entirely different class exists, known as "salts." These salts are crystallized salts of nitric acid or ammonia. They are perfectly soluble in water, and the nitrogen is in an immediately available condition. They contain no organic matter of any kind, but are practically pure chemicals. They are held in very high esteem for all crops, and are of special value for tobacco, but to obtain the best results they should be used on soils naturally rich in organic matter, or made so artificially by the use of manure, castor pomace, muck, or compost.

There is nothing gained in applying these chemicals much in advance of the crop, for they are perfectly available as plant food whenever applied. In this they differ from all the fertilizing materials previously con. sidered. The nitrogen in all animal and vegetable matter is partly inert and cannot be set free until such matter is disintegrated by fermentation. All these organic matters, therefore, require time, in which this fermentation may go on, before the nitrogen contained in them can be utilized by the plant. But experience

shows that, applied as previously directed, these organic manures give up nitrogen to the crop as it can be used. The value of nitrates is modified because nitrogen in this very soluble form is so exposed to leaching. Jenkins has "seen a heavy rain leach away the whole nitrogen supply of a crop where it was in the form of nitrates." It could not do this with organic forms.

The consumption of these nitrogen salts, especially of nitrate of soda, is steadily increasing. There are three of these crystalline salts: Nitrate of potash, which is made by the union of nitric acid and potash; sulphate of ammonia, which is sulphuric acid combined with ammonia, and nitrate of soda, a combination of nitric acid and soda. Of these, the first, nitrate of potash, is rarely used as a fertilizer. It is largely used in the manufacture of gun powder, and commands such a price as to prevent its use for fertilizing purposes. It would seem to be admirably adapted to tobacco culture, owing to its large percentage of both nitrogen and potash, elements especially demanded by this crop, and it should be tried experimentally. Nitrate of potash contains about 14 per cent of nitrogen and 45 per cent of actual potash.

Sulphate of Ammonia.-This valuable salt is obtained in large quantities as a by-product in the manufacture of illuminating gas. It is a white crystalline salt having a slightly bluish tinge and may have a faint odor of ammonia, but it usually is odorless. Its value as an agricultural salt has long been known, and it is largely used for manurial purposes, both in this country and Europe. It is very uniform in composition, and is sold under a guaranteed analysis of twenty-four to twenty-five per cent of ammonia, which is the same es twenty to twenty and one-half per cent of nitrogen. The percentage of free water is very small, rarely over one per cent. It is freely soluble in water, and the