194 
ON VALERIANIC ACID. 
big's view of ammonia infers the same limitation of the ex- 
istence of the organic kingdoms to a few thousand years, as 
is deduced from the hypothesis of organic matter being the 
food of plants. 
Here, therefore, he differed from Liebig, contending that 
ammonia must be produced from the nitrogen of the atmos- 
phere, and showing the probability of what is taught by Pro- 
fessor Johnson, namely, that the nitrogen of nitrates formed 
from the atmosphere, is fixed by plants, as well as the nitro- 
gen of ammonia. In conclusion, he reviewed the evidence 
of potassa, the phosphates, and the other saline matters, of 
both organic kingdoms, being derived originally from the 
crumbling of rocks, and dwelt on the retardation of vegeta- 
ble physiology, by the long scepticism of botanists on this 
head, owing, as he believed, to their distrust in the conclu- 
sions of chemistry ; and went on to show that chemistry 
must be the ground-work of vegetable physiology in its pre- 
sent stage, and that the frequent changes in the aspect and 
nomenclature of chemistry did not materially affect the facts 
which it daily affords for the elucidation of the vegetable 
economy. — Chemist. 
ART. LVI. — EXPERIMENTS ON THE PREPARATION, PROPER- 
TIES AND COMPOSITION OF VALERIANIC ACID AND SOME 
OF ITS SALTS. 
By Dr. C. G. Wittstein. 
Valerianic acid, the salts of which have of late been so 
much recommended, is, as is well known, not solely a 
natural constituent of valerian, but is likewise formed arti- 
ficially in various chemical reactions upon organic bodies \ 
