gto On different Sorts of Lime ufed in Agricultures 
of attempting to difeover the nature of the ingredients fram 
whence the difference arofe. For this purpofe I procured 
fome pieces of cach fort of limeftone, and firft tried whas 
would be their effect upon vegetables, in their natural ftate, 
by reducing them to coarfe powder, and fowing im them the 
feeds of different plants. In both kinds the feeds grew 
equally well, and nearly in the fame manner ag they would 
in fand, or any other fubftance whiel: affords no nourishment 
to Dewan Pieces of each fort of ftone were then burnt 
to linte j j and, after they bad been expofed for fome wecks te 
the air, that dec caufticity might be diminithed, fome feeds 
were fown in them. In the kind of lime which was found 
moft beneficial to land, almoft all the feeds came up, and 
continued to grow as long as they were fupplied with water 3 
atid the roots of the plants had many fibres, which had pes 
netrated to the bottom of the cup in which they grew. Upon 
examining the compofition of this fort of lime, it proved to 
confit entirely of calcareous earth. By its expofare to the 
dir for about three months, it was found to have abforbed 
4-5ths of the fixed air required to faturate it. Im the other 
kind, a few only of the feeds grew, and the plants produced 
from them had hardly any ftalks or roots, being formed al- 
mef{t entirely of the two feed-leaves, which lay quite loofe 
upon the furface. This fort of lime, being fpread upon a 
garden foil, to the thicknefs of about the tenth of an inch, 
prevented nearly all the feeds which had been fown from 
coming up, whilft mo injury was oceafioned by common 
Jimé ufed m the fame mauner. Upon examining the com- 
pofition of this fubltauce, which was fo deftructive to the 
plants, it was difcovered to contain three parts of pure cal- 
careous earth, and two of magnelia. The quantity of fixed 
sir which it had -abforbed, by being expofed for about the 
fame tithe as the pure lime juft errerttitined; was only 42 huns 
dredihs of that combined with it before it was burnt. 
As it feemed probable that the magnefia contained in this 
lime was the caufe of its peculiar properties, the following 
experiments were made, to determine the effects of that fubs 
flance upon the growth of vegetables. Some feeds, chiefly 
of colewort, which were preferred from their growing quickly, 
were 
