On the use of Lime as a Manure. By M. Puvis. Paris. THERE is no one of the useful arts to which the application of chemical science may be made of as much importance as to agriculture. We cannot indeed inquire into the minute and delicate processes by which nature elaborates the inert matters of the soil, and converts them into the living plant; but we can examine that organized vegetable, and find what elements enter into its composition, and by a similar examination of soils can determine whether they contain the substances from which the plant must obtain its growth, or not. If they do not, the addition which will be efficient in promoting the growth being thus determined, chemical researches will again show the source whence it can be derived in the most economical manner. So also soils may contain compounds, which, if the proper food of some plants, may be noxious to others; chemistry will detect these, and point out the means of neutralizing their injurious action.

Instead then of the decreasing fertility of soils which political economists assume, in opposition to some well known facts, or which the general experience of some countries would seem to demonstrate, we might infer that good soils could be kept up to their original state, and inferior soils improved until they became equal to the best: that nothing in fact, except climate would oppose a limit to the approach of agricultural product to the maximum.

Such results, however probable in appearance, have been far from being attained, or even approached. Agriculturists rarely take the trouble to learn even the elements of science, and if the direct force of obvious example occasionally leads to the introduction of new machines and improved processes which are merely mechanical, those which chemical science would indicate are rejected as unintelligible and visionary. On the other hand, the student of science can rarely or never acquire the practical skill, the knowledge of the mode of performing and directing agricultural labour, on which the practical farmer properly prides himself, and without which the best theory will lead to no profitable result.

almost every case. When the gigantic bones of the elephant are known to consist to so great an extent of phosphate of lime, it would be vain to deny that the phosphorus and calcium exist in some state or other in the herbage he feeds upon, as well as the oxygen which forms the other ingredient of the phosphate. So far in fact from those substances which are neglected by chemists being unimportant in the constitution of plants, they must modify the manner in which the other elements combine, and although the vital action does in many cases compel them to enter into combinations in direct opposition to the ordinary laws of chemical affinity, we may in many instances safely attribute the great difference which exists among compounds said to be of the same elements, to the very matters that are usually rejected in the examination. "It is said that putrescent manures serve for the nutriment of plants. But the same might be also stated in relation to substances which improve the soil, which furnish to it matters necessary to render it fertile; which impart to vegetables, the earth and saline compounds which enter as essential elements into their composition, texture, and their products. Such improving substances well deserve to be regarded as nutritive.

"Thus lime, marl, and all the calcareous compounds employed in agriculture, since they furnish to plants lime and its compounds, which sometimes form half of the fixed principles of vegetables, ought also to be considered as aliments, or, which comes to the same, as furnishing a part of the substance of vegetables. Thus, again, wood ashes, pounded bones, burnt bones, which furnish to vegetables the calcareous and alkaline phosphates which compose a sixth part of the fixed principles of the stalks, and three fourths of their seeds, ought well to be considered, and surely are nutritive.

"What thus particularly marks the distinction between the manures which improve the soil and those which are alimentary is, that the former furnish, for the greater part, the fixed principles of vegetables, the earths and salts, the latter the volatile matters which are abundantly diffused through the atmosphere, whence vegetables draw them by suitable organs: and what is more remarkable, is, that the vegetable, by receiving the fixed principles of which it has need, acquires, as we shall see, a greater energy to gather for its sustenance, the volatile principles which the atmosphere contains.

"The greater part of improving substances are calcareous compounds. Their effect is decided on all soils which do not contain lime, and we shall see that three fourths, perhaps, of the lands of France are in that state. Soils not calcareous, whatever may be the culture, and whatever may be the quantity of manure lavished on them, are not suitable for all products, are often cold and moist, and are covered with weeds. Calcareous manures, by giving the lime that is wanting in such soils, complete their advantages, render the tillage more easy, destroy the weeds, and fit the soil for all products. "These improving substances have been called stimulants;

T