Nutrition of. This is a subject on which a variety of opinions has been entertained by modern chemists. Hassenfratz considers carbon as the substance which nourishes vegetables. Ingenhousz, in his work on the nutrition of plants, published in 1793, endeavours to prove, that if carbon has any influence in this respect, it can be only in the state of carbonic acid, as that acid is absorbed and decomposed by vegetables; while the ligneous carbon, furnished by Nature, produces no effect on the expansion of plants. Mr A. Young has endeavoured to demonstrate the same thing by experiments. M. Rafn, a Danish chemist, desirous of discovering the truth amidst these contradictory opinions, made, for three years, a series of experiments; from which he concludes, by the expansion, size, and colour of the plants employed, that carbon, either vegetable or animal, has a decided influence in the nourishment of vegetables. What is new, and particularly worthy of remark in these researches, is, that, according to M. Rafn, the carbonic acid produces exactly the same effect as charcoal of wood.

According to Mr Rafn, coal ashes, on which the German and English farmers bestow such praise, destroy the plants if the soil contains an eighth part of that admixture. The leaves become faded, as if scorched, at the end of from fifteen to twenty days, and the plants themselves die at the end of four or five weeks.

No seed germinates in oil. A single grain of common salt, in 200 grains of water, is sufficient to retard the vegetation of plants, and may even kill them if they are watered with that saline liquor.

Shavings of horn, next to infusion animals, are the most favourable to vegetation; charcoal holds the third rank. For the truth of these opinions, see Vegetable Substances in this Suppl.