1864.] Chemistry. 321 
nitrogen no great separation can be effected by this method; the 
diffusive velocity of two gases being inversely as the square roots 
of their densities, nitrogen exceeds oxygen in activity by about 
6-7 per cent. By experiment, about three-fourths of the theoretical 
separation was actually obtained, and other experiments were then 
instituted, with a view of ascertaining what would be the effect of 
other porous bodies, such as stucco, or earthenware, on atmospheric 
gases, and the result shows that all porous masses, however loose 
their texture, will have some effect in separating mixed gases, moving 
through them under pressure. The air entering a room by perco- 
lation through a wall of brick, or a coat of plaster, will thus become 
richer in nitrogen, in a certain small measure, than the external 
atmosphere. Where such a small difference of specific gravities 
exists the separation of gases is a severe trial to the powers of the 
atmolyser, but with greater disparities of density the separation may 
become very considerable. When an explosive mixture of one 
volume of oxygen and two volumes of hydrogen are transmitted, the 
result is very striking, the hydrogen diminishes from 66°66 to 9°3 
per cent., and the gas ceases to be explosive, a lighted taper burning 
in it as in pure oxygen. In other experiments on the diffusion of 
carbonic acid into_air, the remarkable result was discovered that in 
perfectly still air its molecules spontaneously alter their position, 
and move to a distance of half a metre in any direction in the course 
of five or six minutes, whilst the molecules of hydrogen disperse 
themselves to the distance of a third of a metre in a single minute. 
The Professor considers that such a moleeular movement may become 
an agency of considerable power in distributing heat throughout the 
atmosphere. 
The new element Cesium has been the subject of further investiga- 
tion by Bunsen ;* he separates it from Rubidium by converting the 
two metals into tartrates, and adding a sufficient excess of tartaric 
acid te convert the rubidium into bi-tartrate whilst the cesium salt 
remains neutral. The mixture is then exposed in a funnel to an 
atmosphere saturated with moisture, when the neutral cesium salt 
deliquesces and runs through, while the acid rubidium salt remains 
behind. Bunsen has deduced, from cesium compounds so purified, 
the equivalent 132-99; whilst Johnson and Allen, working with very 
much larger quantities of material than Bunsen was able to obtain, 
deduced the number 133-03. These fully authorize the use of the 
round number 133 as expressing the combining proportion of this 
element. 
The very rare metal Vanadium is likely to be somewhat more 
available for scientific research, if not for practical applications, now 
that Riley + has found it to occur in the Wiltshire oolitic iron ore and 
in the pig-iron smelted from it. He finds that this pig-iron will 
readily furnish any quantity of vanadium with tolerable facility ; it 
appears to contain more vanadium than that made from the Taberg 
* Poggendorf’s ‘ Annalen,’ cxix. 1. 
+ ‘Journal of the Chemical Society,’ New Series, ii. 21, 
