like the following opens up new fields of research scarcely dreamt of before: "When we behold the wide turf-covered expanse, we should remember that its smoothness, on which so much of its beauty depends, is mainly due to all its inequalities having been levelled by worms. It is a marvellous reflection that the whole of the superficial mold over any such expanse has passed, and will again pass, every few years through the bodies of worms. The plow is one of the most ancient and most valuable of man's inventions; but long before it existed the land was, in fact, regularly plowed by earth-worms." Surely, in view of such revelations as these, agriculture will not confine itself to the laboratory of the chemist, or rely solely on analysis. The plant and the animal are not to be studied as mere compounds of chemical elements, but as distinct and peculiar individuals with varied and multiplied powers of their own. Above all, agriculture is not to be considered from the standpoint of any one science. The man that would approach it as a victor must come full panoplied, armed, it is true, with the sword of chemistry, but clad with mail composed of links forged from every cognate science-botany, zoölogy, and physiology, physics and meteorology, mineralogy and geology, mechanics and applied mathematics.

EXPERIMENTS TESTING CHEMICAL FERTILIZERS.

Plats 1-16 acre each. Drilled October 27 and 28. Four pecks Fultz wheat per acre.

The plats of this section begin at CIII and run through CXXVII. The first four were in the depression already mentioned, and their results must therefore be compared with 18.04 bushels, the average of the three unfertilized plats; all the others are to be compared with 15.86 bushels, the average of the two poorest unfertilized plats.*

*The paper is but one in a series by the author. The data taken has been already established.

Examining first the four plats situated in the depression, and fertilized with mineral matters, we find that 200 pounds of acid phosphate of lime on CIII give an increase of 2.49 bushels per acre, 200 pounds of sulphate of potash on CIV an increase of 2.22 bushels, 200 pounds of sulphate of magnesia on CVI an increase of 2.76 bushels, and 200 pounds of muriate of potash on CV an increase of 3.29 bushels. The larger gain in the last named plat was, perhaps, due in part to the increased amount of potash afforded by the muriate, and in part to its chlorine. Two hundred pounds of plaster (hydrated sulphate of lime) gave an increase of 0.67 bushels, as shown by previous experiment. Next comparing together the plats on which these mineral matters were applied, two by two, we are again able to discover, with a single exception, but slight differences in the results as compared with the unmanured plats and with the preceding. For example, a dressing of the sulphates of potash and magnesia on CXXV gave an increase of 1.20 bushels per acre, one of the sulphates of potash and lime on CXXVI an increase of 0.14 bushel with a remarkable increase of straw in this plat; one of sulphate of lime and muriate of potash an increase of 2.54 bushels. The exception was CXX, on which an application of muriate of potash and acid phosphate of lime gave an increase of 4.40 bushels. It appears that used alone the muriate of potash increased the crop of grain by 3.29 bushels, and the acid phosphate of lime by 2.49 bushels; used together, by 4.40 bushels per acre. With this exception, these salts mixed together gave results inferior to those afforded by their separate applications. It will be noticed that the muriate. of potash, both separately and in combination, gave better results than the sulphate.

Experiment CXXI was introduced to test the relative effects of soluble and insoluble phosphoric acid. In CXX, where the soluble acid phosphate was used, the increase was 4.40 bushels; in CXXI, dressed with the very sparingly soluble bone phosphate, it was about 50 per cent. less, or two bushels per acre.

If we examine, finally, the plats dressed with the mineral salts combined by threes, we observe that a combination of acid phosphate of lime, sulphate of potash, and sulphate of lime on CXIV gave the very slight increase of 1.47 bushels per acre. A

combination of the sulphates of magnesia, potash, and lime on CXXIV gave better results, an increase of 3.87 bushels. Singly or in combination, the magnesia proved superior to the phosphate.

If anything can be safely inferred from such slight differences as these, it is that the soil was somewhat richer in phosphoric acid than in potash; that it required magnesia, perhaps also chlorine, and that the effects of the mineral salts in combination were somewhat neutralized by their mutual reactions, or by the influence of the soil.

We come next to the plats on which nitrogenous salts were applied. This brings up the subject of nitrogen, perhaps the most important in the whole domain of agricultural science. Can plants avail themselves of the nitrogen of the air, or must this element be supplied to them in the shape of manures? The importance of nitrogenous manures has been discussed before to-day. Johnson, in his introduction to "How Crops Grow," remarks that the earliest book in our language on the subject of chemistry applied to agriculture was published by the Earl of Dundonald in 1795. It may have been the first original treatise, but I have before me a work of singular interest, entitled "The Natural and Chemical Elements of Agriculture, Translated from the Latin of Count Gustavus Adolphus Gyllenborg," which was published in London in 1770. In this work the Swedish author attempts to deal with the scientific principles on which the art of agriculture depends. In the chapter treating "Of Salts as Promoting Vegetation," he uses language which shows that the merits of nitrogenous salts were as warmly disputed over in the days of yore as they are now: "The report in favor of nitre is still greater. Mayow, in Fr. de Nitro, Glauber, Bacon, Digby, Lemery, Vallemont, Nieuwentut, and all who have copied them, or rather written of nitre, hold it forth as the only thing—as the very soul of vegetation and growth, and without which all ceases. The writers on husbandry support their opinion-1. By the praise bestowed on nitre by the ancients. 2. By its being of celestial origin, and present everywhere. 3. By its being found in vegetables, on the burning of which it is turned to an alkaline salt, the nitrous acid being evaporated by heat. 4. By its fertilizing powers being confirmed

by many experiments; for we find that even dung is converted into a nitrous earth, and, being thus changed, exerts a surprising power of fertility." He goes on to controvert these propositions, and remarks that "the nitre of the ancients was the natron or mineral alkali,” a very different substance "from our nitre." While admitting that “nitre is of celestial origin in one respect, namely, its acid," he asserts that "no real nitre has ever yet been found in the air," although "nitrous acid is indeed scattered in our atmosphere."

Liebig held that the atmosphere was capable of supplying, either directly or indirectly, all the nitrogen required by agricultural plants; and hence, that applications of nitrogenous matters were unnecessary and useless. Boussingault denied this power to all except leguminous plants, and maintained that they could only appropriate nitrogen through the medium of the soil, and in the form of ammonia and nitric acid. Ville asserts that plants can assimilate either the nitrogen of ammonia and the nitrates, or the free nitrogen of the air. Boussingault, Gilbert, Lawes, and others, have questioned the accuracy of Ville's experiments tending to establish the latter point, and have brought forward others supporting the opposite conclusion, namely, that plants cannot directly assimilate the uncombined nitrogen of the air. In combating Ville's theories, Lawes has quite recently made the following emphatic declaration: "I maintain that the amount of nitrogen supplied to our crops from the atmosphere-whether as combined nitrogen brought down by rain, or that absorbed by the soil, or the plant-constitutes but a very small proportion of the total amount they assimilate; and that the soil itself (or manure) is practically the main source of their supply. Indeed, it is a question whether, on arable land, as much or more may not be lost by drainage, or otherwise, than is supplied by the atmosphere." Warrington is equally positive in the expression of his opinion: "Besides carbonic acid, plants are apparently capable of absorbing a small quantity of ammonia through their leaves. The uncombined nitrogen of the atmosphere is not appropriated by plants."

Several writers, among them Johnson, hold that while agricultural plants may not have the power of appropriating directly the nitrogen of the air, they can do so indirectly. Admitting