299 
Nutrition of V egetables . 
| Sixty- three of these plants when dried weighed 372 gr. Inci- 
nerated they left 54.2 gr. of gray ashes. These afforded by lixivi- 
ation 18.6 of very fine potash. From this I am inclined to think, 
that the radish might be cultivated with advantage on wet sandy 
places by the sea shore, for the purpose of fabricating potash.* 
These 18.6 gr. being farther analysed, were found to contain 6*7 
of pure potash; 7*35 of sulphate of potash; a small quantity of 
i phosphate of lime ; and the rest was carbonic acid. 
The residuum left after lixiviating the ashes appeared to con- 
tain sulphur, as on pouring nitric acid over it sulphuretted hydro- 
gen was given out ; but 1 could not find any phosphoric acid in 
it. I did not examine it for the earths, as these might have been 
said to have been taken up from the sand, 
* It appears, that potash abounds in all the plants of the class tetradyna- 
mia, and the ashes of some of the species were long in use for making soap and 
glass, before the introduction of soda as an article of trade. According to 
Bomare, the bunias cakile, sea rocket, was much employed for these purposes, 
I must here add an observation, which appears to me pretty general, and 
which I made in examining the acrid and bitter properties of plants. One or 
other of these principles I have almost always found in conjunction with a 
large quantity of potash, which was frequently saturated with nitric acid. 
Thus among the cruciferous plants, which are all more or less acrid, the si- 
symbrium nasturtium, common water-cress, afforded me a gi eat deal of alka- 
line matter after incineration ; and when fresh I found in it nitrate oi potash, 
I have observed the nitre melt on incinerating cabbages and turnips ; and 
Mr. Delaville found this salt in large quantity in the sap of these plants. 
Mr. Bouillon-Lagrange found a large quantity of potash in the ashes of the 
erifferon canadense, Canada fleabane, which is acrid. The ashes of tobacco, 
the acrimony of which is well known, yield 40 per cent, of potash. Among 
the bitter plants I have examined, I found nitrate of potash in the fumitory, 
100 parts of the ashes of which contain more than 36 soluble in water, ac- 
cording to Wiegleb and Rukert. The common centaury, marsh and Siberian 
trefoil, and different species of the genus centaurea, which are very bitter, 
afford ashes in which potash abounds. Whether in these plants it be satura- 
ted with nitric acid I have not ascertained. I must observe, however, that I 
have found no nitric acid in wormwood, 100 parts of the ashes of which afford 
nearly 75 of saline matter, according to Wiegleb. This large quantity of al- 
kali has appeared to me to be partly saturated with a peculiar matter, which 
is deposited by a decoction of the fresh plant, and may be precipitated abun- 
dantly by nitrate of lead. This matter dissolves very well in alkalies neutra- 
lizing part of their properties : it is the same that Mr. Vauquelin has found 
in some species of cinchona. Does it exist in all bitter plants ? and is it this 
which in cinchona and worm-wood cures intermittent and low fevers ? 
i 
