(; AMy J 
concludes, that gypsum takes from the atmosphere 
the elements of vegetable lifeand transmits them di- 
rectly to plants. Bosc intimates, that the septic 
quality of gypsum (which he takes for granted) best 
explains its action on vegetation; but this opinion is 
subverted by the experiments of Mr. Davyy—who 
found, that-of two parcels of minced veal, the one 
mixed with gypsum, the other left by itself, and both 
exposed to the action of the sun, the latter was the 
first to exhibit symptoms of putrefaction. Mr. Da- 
vy’s own belief on this subject is, that it makes part 
of the food of vegetables, is received into the plant 
and combined with it. The last opinion we shall 
offer'on this head, is that of the celebrated Chaptal. 
Of all subsiances, gypsuin is that of whose action 
we know the Jeast.. The prodigious effect it has on 
the whole race of trefoils (clover, &c.) cannot be 
éxplamed by any mechanical agency—the quantity 
applied being so small——nor by any stimulating pow- 
er—since gypsum, raw or roasted, has nearly the 
same effect ; nor. by any absorbent quality, as it only 
acts when applied to the leaves. If permitted to 
conjecture its mode of operation, we should say, 
ihat its effects being greatest when applied to the 
wel leaves of vegetables, it may have the faculty of 
absorbing and giving out water and carbonic acid, 
little by little, to the growing plant. It may also 
.be considered as an aliment in itself—an idea much 
supported by Mr. Davy’s experiments, which shew, 
that the ashes of clover yield gypsum, though the 
clover be raised on soils not naturally containing 
that substance.” 
