“arn substances contained in it, to the 0 water; this las 
evaporation in a water-bath gave a white salin ass, from which acta 
extracted urea in such a state of purity as to cepitallios on evaporati 
i iAnn. der Chem. und Pharm., exxi, 1, and Phil. Tr rans., 1861. 
 _ Ina note to the above paper Liebig calls attention to the fact that 
E Graham’ s explanation of the diffusion of saline solutions through space 
: media, i is ap gt with that which he had himself given in a paper o 
the causes of the motion of setae: ~ the animal body published a 
1848, at which Graham appears to have seen. Liebig further 
: ustrates the importance of the ae in examining the animal fluids, 
by a statement that flesh-broth, obtained by heating two parts of 
with one of water in a water- -bath, gave on dialysis an almost perfectly 
colorless diffusate, from which after concentration in a water-bath, v 
pure crystals of creatin were de posited, the other erystallizable subsinaeies 
in flesh being also present in the liquid. By a similar process, Liebig 
detected alloxan in a mucous discharge from the bowels. ‘The import- 
ance of the method in the study of the chemical constitution of animal 
and vegetable secretions, can hardly be over estimat Ww. G. 
upon a vapor in sich a manner that its co-efficient of expansion for tem- 
peratures which lie near its point of evaporation, approximates to the 
co-efficient which aan at the highest temperatures. 
uthors remark that the mixture of a permanent gas may aid in 
distinguishing between the cases in which a vapor bas an unusually high 
co-efficient of expansion and those in which an ac chemical change 
Occurs. It is also possible by the employment o of a permanent gas ve 
peeenne the vapor densities of ss tg ees, which cannot be 
e boili int without decom 
In ha one % of those substances which may be heated aban their 
ing points, ihe authors employ Gay-Lussac’s process for the determina- 
sino the vapor density. ‘i slight modification of the process is how- 
ecessa Before the g 
calculation, the volume of the hydrogen reduced to 
gall hl dik mcriawe measured with the ial eae ons. In 
subsequent the - 
