412 Scientific Intelligence. 
(8.) Water expels mercury from the pores of charcoal by an instanta- 
neous action 
(9.) The action of porous bodies is not discriminate but elective. 
Theoretical Considerations, 
(1.) The elective nature of porous bodies may be closely allied to three 
properties :— 
a, The condensibility of the gases. 
b, The attraction and perhaps inclination to combine. 
c. The capacity of combination. 
(2.) In either case, the attraction which results in condensation of the 
gas is exercised at distances greater than the distances of atoms or mo- 
lecules in combination, 
(3.) The gases in porous bodies lie in strata, the outside and more dis- 
tant being less attracted than the atoms nearer the solid bo 
of two kinds ; and it seems more in accordance with Nature to diminish 
than to increase the number of original powers.—Proceed. Royal Soe'y, 
Feb. 5, 1863, p. 424. 
ti 
ent kinds of charcoal on ammoni rbonic acid and cyanogen 
He found that prolonged heating of charcoal diminished its power of 
absorption, hence all the pieces of charcoal were heated as nearly equally 
as possible. We condense below his main results, giving the mean of 
all the trials reduced to 0° C. and 760 mm. 
Ammonia. Carb.acid. Cyanogen. Ammonia. Carb.acid. Cyanogen. 
Logwood, 111-3 546 87:3 |Logwood, } 49.5 83°38 33°3 
Ebony, 106°7 47.0 89°6 (Jamaica ) a 
Cam wood, 91:2 45-4 Sapan wood, 69°9 822 322 
Green Ebony, 90.3 40°8 Beach, 58° : 
Fustic (Cuba), 896 _— 580 Rosewood, 506 
81-2 288 |Sinensis, 
i Negeale ' 505 573] 
, 
* 
