5S ON ACHILLE1NE AND ACHILLE1C ACID. 
stantly destroyed by chlorine ; it is not precipitated by tinc- 
ture of galis nor acetate of lead, but it is thrown down by 
basic acetate of lead ; it is soluble in ammonia, and the so- 
lution, when exposed to the air until the ammoniacal odour 
has disappeared, deposits brown flakes, which are less solu- 
ble than achilteTne* From all its properties it should un- 
doubtedly be ranked with the bitter extractive substances. 
To obtain the acid to which the decoction of the yarrow 
owes its acid reaction, the author treated it with acetate of 
lead as long as a precipitate resulted, and this was suspended 
in water and decomposed with sulphuretted hydrogen. The 
liquid obtained was very acid, and still contained some 
green coloring substance and lime ; it was, therefore, super- 
saturated with carbonate of potassa (which precipitated the 
lime) and then treated with animal charcoal. The potassa- 
salt was precipitated with acetate of lead, and the precipi- 
tate decomposed with sulphuretted hydrogen. 
Achillei'c acid is not volatile at 212° F. ; its solution can 
therefore be concentrated by evaporation in the water-bath. 
The greatest concentration to which it can be brought is 
1.014825. In this state it is perfectly colorless, but on fur- 
ther evaporation it becomes straw-colored. Exposed to the 
air in a glass or porcelain dish, it crystallizes in perfectly 
colorless quadrilateral prisms. The crystallised acid requires 
at 56° F. two parts of cold water for solution ; the solution 
is very acid, makes the teeth rough, has no odour, and 
strongly reddens litmus paper Added by drops to a clear 
solution of acetate of lead, it it does not render it in the 
least turbid ; but in a solution of basic acetate of lead it 
immediately produces a white precipitate, which is very 
slightly soluble. 
Achilleate of potassa is obtained when the acid, diluted 
with only a little water, is poured into a solution of car- 
bonate of potassa, so as to neutralize it ; the liquid is then 
filtered, evaporated, and set aside to crystallize. This salt 
separates in very minute prisms, which can only be seen 
with a microscope ; it has a saline taste, which resembles 
