148 ABSORPTION OF SALINE SUBSTANCES BY CHARCOAL. 
as was the case with the acetate of copper, when the affin- 
ity of the charcoal was weakened by mechanical means by 
isolating the molecules, the water is able to re-take up the 
salt which it had previously abandoned. 
This explanation, which I venture to propose will, I think, 
not appear surprising, for we are prepared for it by the be- 
haviour of charcoal under other circumstances. The way 
in which it removes lime and calcareous salts is a phenom- 
enon of pure absorption ; there can have been no reduc- 
tion in such a case. Messrs. Bussy and Payen have satis- 
factorily demonstrated that there is no chemical action in 
the decoloration of liquids ; and the way in which it com- 
bines with the bitter principles of vegetables can only be 
explained by a peculiar affinity. 
The attention of chemists was called to this new and cu- 
rious property by Mr. Warington. It had, it is true, already 
been pointed out by M. Duburgua, who had long before 
stated that tincture of gentian was entirely deprived of its 
bitterness by being filtered through charcoal ; by M. Cheva- 
lier in 1826; by M. Holph in 1831 ; and M. Rhighini six 
or seven years back, who advised the use of charcoal as an 
excellent plan for obtaining the bitter principle of worm- 
wood. 
Notwithstanding all these experiments, the property 
which this substance possesses of combining with certain 
organic principles was nearly forgotten, when, in 1845, Mr. 
Warington again called the attention of chemists to it. 
Having been requested by a brewer to find a convenient 
and easy method for decolorizing large quantities of brown 
ale, so as to give it the appearance of pale ale, he immedi- 
ately thought of charcoal. The beer was decolorized, but 
had become perfectly insipid. Little prepared for such a 
result, Mr.Warington repeated his experiments upon differ- 
ent kinds of beer, and lastly upon infusions of hops, worm- 
wood, decoctions of gentian, nux vomica, and even aloes 
