This compound was formerly regarded as a soap; doubtless because wool contains beside the suint a considerable proportion (about 83 per cent.) of greasy matter, (Chevreul.) This grease, however, is, in fact, combined with earthy matter, chiefly lime, as an insoluble soap. The soluble sudorate is, according to MM. Maumené and Rogelet, a neutral salt, resulting from the combination of potash with a peculiar animal acid, of which little is known beyond the fact that it contains nitrogen.

At the great seats of the woolen manufacture in France, as at Rheims, Elbœuf, and Fourmies, the new industry of MM. Maumené and Rogelet, is either established or in course of establishment. Their plan is to buy of the woolen manufacturers the solutions of suint obtained by the immersion of their raw fleeces in cold water; paying higher, of course, for those liquors in proportion as they are stronger; thus, for example, for the suint from a ton of wool they pay five francs, if diffused through 27 hectolitres of water, (sp. gr. 1.030;) whereas, for the same quantity of suint they can afford to give no less than 18 francs, if it be concentrated in 3 hectolitres of water, (sp. gr. 1.250;) and so in like proportion for the suint liquors of intermediate strength.

An ordinary fleece, weighing four kilograms, contains, according to MM. Maumené and Rogelet, about 600 grams of sudorate of potassium or suint. This, according to their analysis, should contain 33 per cent. of its weight, i. e., 198 grams of pure potash. Of this, according to another estimate, (showing the nitre it would produce,) they appear to reckon on about 173 grams as being practically recoverable.

The wool manufacturers of Rheims wash annually 10,000,000 kilos of fleeces, those of Elbœuf 15,000,000 kilos, and those of Fourmies 2,000,000 kilos-total 27,000,000 kilograms, the produce of 6,750,000 sheep. From this quantity, were it all subject to MM. Maumené and Rogelet's treatment, 1,167,750 kilos of pure potash would, according to the above ratio, be recoverable. The value of the potash, as carbonate, reckoned at the average price of American potash, would range between $400,000 and $450,000. The wash-water yielding it, if paid for at MM. Maumené's and Rogelet's minimum price, would cost about $100,000. Hence it appears that the process of MM. Maumené and Rogelet may be worked on a large scale and with very ample profit. MM. Maumené and Rogelet compute that there are 47,000,000 sheep in France-nearly seven times as many as those above calculated on. And they point out that if the fleeces of these were all subjected to the new treatment France would derive from her own soil all the potash she requires; enough, they observe, to make 12,000,000 kilograms of commercial carbonate of potash, convertible into 17,500,000 kilograms (about 17,500 tons) of saltpetre; with which, as they characteristically add, 1,870,000,000 cartridges could be charged. The difficulty of collecting the wash-waters of fleeces, scoured in small numbers by the farmers all over the country, is a great bar to such an extension of the process.

The value of potash as a manure is naturally indicated by the com

EMPLOYMENT OF POTASH SALTS IN AGRICTLTURE.

position of all land plants, for they rob the soil of more or less of this constituent. As a general thing, in our rich and virgin soil there is potash enough to supply vegetation for a long time, particularly as the slow decomposition of the particles constituting the soil liberate more or less of this alkali. In Europe, however, the case is different, and every artificial means is resorted to to restore and replenish the potash of the soil. The new and abundant mineral source of potash salts has awakened the attention of agriculturists in Europe, and now the only question for solution is the best way of applying them. On this subject opinion is still divided, but it has been satisfactorily ascertained by experiments in both France and Germany that practical benefit can be derived from them. Owing to the fact that potash in the United States is too costly for agricultural purposes, and that there is no likelihood of its being resorted to at present, no details will be given of the European experiments. The chloride of potassium is the salt generally used.

CHAPTER IV.

AMMONIA, BARYTA, MAGNESIA, AND ALUMINA.

AMMONIA AND SALTS OF AMMONIA-APPARATUS FOR MAKING AQUA AMMONIA-DETAILS OF THE OPERATION OF DISTILLING-BARYTA AND ITS COMPOUNDS-PERMANENT WHITEMAGNESIA AND THE MAGNESIA-SALTS-OXYCHLORIDE OF MAGNESIUM; ITS PROPERTY OF SOLIDIFYING-ALUMINA AND ITS COMPOUNDS-ALUMINATE OF SODA; ITS USES IN DYEING ALUMINA-SULPHATE OF ALUMINA—ÀCETATE OF ALUMINA—ÁLUM.

AMMONIA AND AMMONIA SALTS.

But little advance has been made in the manufacture of the ammonia compounds. Ammonia is now derived almost exclusively from gas works, it being one of the products of the distillation of coal in the manufacture of gas. It is true that coal contains but very little nitrogen, not averaging over one per cent., but when it is recollected what an immense quantity of coal is used in making gas, even this small quantity of nitrogen yields in the aggregate a large amount of ammonia. In London over 1,000,000 of tons of coal are used annually in making gas, and supposing one-third of the nitrogen to enter into the formation of ammonia, this amount of coal will represent about 10,000 tons of sal ammoniac. But even this source of ammonia does not meet the demands of the arts, especially as it is largely taking the place of potash in alum and other compounds. A still larger amount of coal is used for other purposes than making gas, and in many instances is so burnt that with but little ingenuity it may be made to increase the yield of ammonia when it becomes an object. The coking furnaces would be a prolific source, and already in the Paris gas works much coke of a very beautiful quality is made in coking ovens, and the gas as well as all other volatile products are saved.

The manner of procuring ammonia from the weak ammoniacal liquors is carried on with more system and economy in the Paris gas works than in any other works I visited. In the first place the liquors are not carried over two or three hundred yards, when they are emptied into a system of vats from which they are pumped into pans and neutralized by sulphuric or hydrochloric acid and crystallized and purified; or they are conducted to a set of stills, most ingeniously devised, but which could not be fully explained without a number of drawings. It is a system of stills and condensers, so arranged that their operations are nearly automatic, where the water is treated with caustic lime, and the ultimate result is an ammonia of every variety of commercial strength and of a sufficient degree of purity to be put upon the market at once. It is in part like the apparatus figured below for making ammonia in the moist way from the ammonia salts of commerce.

APPARATUS FOR MAKING AMMONIA.

The following is a description of a form of apparatus which I devised several years ago, and with which I have made large quantities of ammonia at a very economical rate and without the slightest incon venience to the operator. It can be made of any required size. Its construction and arrangement are clearly shown by the accompanying figure, (Fig. 4) on page 47.

REFERENCES TO THE FIGURE.

A, retort of sheet-iron with a man-hole at the end; B, feed-pipe for solution of sulphate of ammonia; C, feed-tub, (half of a barrel;) D D', washers; E E' E", gas pipe; F F', safety tube of one-eighth inch glass tubing; G, cooling and condensing coil, placed in a 42-gallon barrel: H, traps of one-half inch block tin pipe to run off condensed aqueous

Fig. 3.

Tin cap for neck of carboy.

ammonia; I I', bottle No. 1; K K', bottle No. 2; L, two-gallon stoppered bottle to receive aqueous ammonia.

Fig. 3 shows the manner in which the tin cap and glass tubes are fitted on the neck of the carboy bottles I and I'. a is a finch tube which reaches to near the bottom of the carboy; b is a safety glass tube of one eighth of an inch; c is the exit tube which connects I with K.

The joints of the lead pipe are wrapped with bladder, while those of the glass or tin pipe are made with pieces of India-rubber tubing.

The tin caps on I and l' are wrapped with bladder. Those on K and K' are loose.

DETAILS OF THE OPERATION OF DISTILLING.

I. Introduce into each of the carboy bottles II' and K and K' five gallons distilled water, unless some weak ammonia is left from previous distillation, when substitute six gallons of this in I and I'.

II. Introduce into D and D' water up to the mark X and X'.

III. Introduce into L sufficient water to cover the orifice of the trap H. IV. Introduce into A 100 pounds fresh lime, lute the manhead in and bolt securely.

V. Having secured all the joints, allow a solution of 120 pounds sulphate of ammonia in 40 gallons water to flow from the tub C, through pipe B into A, and allow the apparatus to stand until next morning.

VI. Early in the morning proceed to distillation. By the aid of a gentle fire, the intensity of the distillation is regulated by safety tubes F F, from which none of the wash water should be ejected. If the latter occurs the fire must be dampened.