ON VALERIANIC ACID. 195 
for instance, in the action of caustic potash upon potato 
fusel oil. Admitting however that the artificial acid is per- 
fectly identical in a therapeutical point of view with the 
natural, yet the most advantageous method of obtaining it 
appears for the present still to be from the plant. 
Preparation. — The author brings for this purpose 20 lbs. 
(18| oz.) of dry and finely-cut valerian root with 100 lbs. 
of water into a copper still, and draws off 30 lbs. The re- 
cipient employed is a Florence flask, in order not to lose 
the sethereal oil, which constantly amounts to 3 — 3^ oz. for 
every 20 lbs. of root. 30 lbs. more water are added to the 
residue in the still, as much drawn off, and this addition 
and distillation repeated once more. The root is then so 
exhausted that what passes over no longer reddens litmus ; 
the contents of the still, however, turn litmus red; but this 
does not arise from valerianic acid, but from another non- 
volatile organic acid. No addition of acid, as recommended 
by Rabourdin to liberate the valerianic acid, is consequently 
requisite. The three aqueous distillates are saturated after 
removal of the essential oil with carbonate of soda, evapo- 
rated in a copper vessel to within a few pounds, then fil- 
tered and evaporated to dryness on a sand-bath in a coun- 
terpoised porcelain dish. Having ascertained by weighing 
the amount of valerianate of soda, it is dissolved in an 
equal weight of water, poured into a retort of 6 to 8 times 
the capacity, and a mixture consisting of 1 part concen- 
trated sulphuric acid and 2 of water added, so that there be 
4 parts of concentrated acid for every 5 parts of dry valeri- 
anate of soda. The soda instantly combines with the acid, 
forming sulphate of soda, and the liberated valerianic acid 
floats as a brown oil on the saline solution. By distillation 
in the sand-bath it passes over along with the greater por- 
tion of the water. The contents of the recipient are emp- 
tied into a tall cylinder, left some time in quiet, and the oily 
acid separated from the subjacent aqueous layer ; the aque- 
ous solution is likewise preserved, being a concentrated 
