34 
FACTS AND OBSERVATIONS. 
which is placed within a shorter tube of glass, and secured 
in its position by corks, so as to appear like a Liebig's con¬ 
denser. The glass tube is placed in communication with an 
air-pump, and the annular space betw T een the two tubes 
maintained as nearly vacuous as possible. Air, or any other 
mixed gas, is then allowed to flow in a stream along the clay 
tube, and collected as it issues. In the gas collected, the 
denser constituent is thus concentrated in an arithmetical 
ratio, while the volume of the gas is reduced in a geome¬ 
trical scale. 
Hippuric Acid in the Urine of Cattle. —Dr. Thu- 
dichum observes, after referring to the observation that 
whenever benzoic acid, or other compounds of the benzoyl 
series was taken into the stomach, it always appeared as 
hippuric acid in the urine; that with regard to the food of 
cattle, there is no reason to suspect the existence of benzoyl 
compounds either in mangold-wurzel, grass, or hay, but 
hippuric acid is, nevertheless, voided in the urine. There 
are some curious anomalies in this respect already published ; 
thus, Liebig has found hippuric acid in larger quantities in 
the urine of stall-fed cattle and of horses kept for pleasure, 
whilst in the urine of animals used for ploughing or other 
hard work benzoic acid was found instead. Lemann also 
found hippuric acid, but he remarked that by fermentation 
the same sample of urine gave benzoic acid. There is a 
difference induced by the kind of food consumed by cattle. 
Thus, grass-fed oxen furnished hippuric acid in the urine, 
but on the day their food was changed to clover, oats, or 
brewer's grains, this ordinary product vanished. Riley has 
likewise remarked that hippuric acid is more abundant in the 
urine of grass-fed cattle. 
Potash in the Perspiration of Sheep.—A patent has 
been taken out in this country by MM. Maumene and Roge- 
let, although never worked, for obtaining potash from snint, 
the name given by them to a compound of potash and some 
organic acids secreted in the sweat of sheep, and found on the 
wool. It is easily soluble in water and separated from the wool 
by merely washing it; the solution is then to be evaporated, 
and the potash obtained by lixivation and calcination. Suint 
constitutes about 15 per cent, of the weight of the raw fleece, 
and yields 33 per cent, of potash, so that if all the scourings 
of the wool produced were worked, the supply of this 
alkali from this source would be considerable. 
