FLOWER OF THE ARNICA MONTANA. 
403 
imperfectly fecund; yet there were others that possessed the 
power of reproduction, either with stock species or among' 
themselves. He is also of opinion that such commingling of 
species occurred much oftener than is usually thought to be 
the case. 
NEW METHOD OE DETECTING NITRIC ACID IN THE 
DRY WAY. 
Professor W. Stein gives a method for detecting nitric 
acid in the dry way when combined with bases. When 
heated the nitrates of potash and soda give off oxygen, and 
form fixed nitrites. The nitrates of baryta, strontia, and 
lime, together with those of magnesia, alumina, and the 
heavy metals, when heated, give up the nitric acid, which is 
split into oxygen and nitrous acid. As however we do not 
always know with what base the acid may be combined, the 
author recommends the following mode of testing:—He heats 
the substance in a test-tube either with bisulphate of potash 
or oxide of lead, placing in the upper end of the tube a strip 
of filtering-paper moistened with a slightly acid solution of 
pure sulphate of iron. If the nitrates are present only in so 
small a quantity that the nitrous vapour is not itself percep¬ 
tible, the paper becomes of a yellowish-brown colour. In 
this way the author discovered the 2000th part of nitric acid 
in a mixture, which by the usual moist way would have been 
impossible. The process is particularly applicable for the 
detection of nitric acid in spring waters. In applying the 
test it is necessary to guard against heating the paper. In 
the presence of chlorides the employment of bisulphate of 
potash is objectionable, because the liberated chlorine colours 
the paper by forming chloride of iron. The presence of prot¬ 
oxide of iron or much organic matter in the substance also 
interferes with the bisulphate of potash test. 
CONSTITUENTS OE THE FLOWER OE THE ARNICA MONTANA. 
The flowers of Arnica montana have been analysed by 
Walz who found them contain a bitter principle, Arnicin= 
C 70 H 54 Oi 4 , an ethereal yellow oil, two resins—one soluble in 
ether, the other not—tannin, a yellow colouring matter, a 
white fat melting at 28°, and a waxy matter. 
