Mr. Warington on the Action of Animal Charcoal. 271 



quantities to their beer to give it a more intoxicating power. 

 1 therefore digested some nux vomica in coarse powder with 

 a part of the ale prepared for the previous experiments, and 

 on passing this when cold a great number of times through the 

 charcoal the bitter flavour still remained, and hence I con- 

 cluded at the time that my hypothesis was correct. Other 

 engagements broke in on my experiments at this time, and 

 prevented my prosecuting the investigation further. 



About ten days since, however, I was recalled to this subject 

 by some other experiments, and tried the effect of animal 

 charcoal on the decoctions of some other astringent bitter 

 substances, as oak bark, Peruvian bark {Ci?ichona cordifolia), 

 and others, all of which had their flavour entirely removed. 

 It may be as well to mention here, that in this second and also 

 in a subsequent series of experiments the animal charcoal was 

 added to the warm solution of the material under trial, and 

 they were digested together on a sand-bath until the full effect 

 had taken place, after which the fluid was passed through a 

 filter. The charcoal used was the ordinary bone-black of the 

 sugar-reflner purified by digestion with hydrochloric acid, 

 washed as long as any saline matter was abstracted, and then 

 dried and heated to low redness. I then tested the extent of 

 this extraordinary power of charcoal by suiimitting a decoc- 

 tion of aloes to its action, with the same results, the whole of 

 the bitter flavour being removed. 



I had proceeded thus far when I was referred by my friend 

 Mr. Henry to a work published at Breslau in 1842, by MM. 

 A. Duflos and A. Hirsch, entitled Okonomische Chemie, where, 

 under the article Beer at page 65, I found nearly all that I 

 had observed described in a few words ; namely, that the bit- 

 ter of the hop, and of all other vegetables used as substitutes 

 for it, as gentian, wormwood, &c., and even aloes, was removed 

 by animal charcoal, but that the bitter of nux vomica, which 

 is often made use of in England, was not affected. 



On looking over my experiments, however, my attention 

 was arrested by finding that the decoction of the bark of the 

 Cinchona cordifolia had had the whole of its bitter removed. 

 Now, on the grounds stated in the previous part of this paper 

 regarding the active principle, this should not have been the 

 case. I therefore took a small quantity of disulphate of quina, 

 dissolved it by heat in distilled water, and then added the 

 charcoal, and discovered that the whole of the bitter was re- 

 moved in less than a minute. A solution of acetate of mor- 

 phia was also submitted to the action of charcoal with a like 

 result. A watery solution of strychnia was similarly affected, 

 and this made it necessary to repeat my former experiment on 



