Intelligence and Miscellanies. 993 



49. Decoloring action of Charcoal. — An elaborate me- 

 moir on this subject, by Mr. Bussy, which obtained the prize 

 proposed by the Society of Pharmacy, of Paris, contains the 

 follovviiig results : 



1. That the decoloring property inherent in charcoal, 

 manifests itself only when the charcoal is in certain physical 

 conditions, among which, porosity and division hold the first 

 rank. 



2. That the azote is devoid of effects ; that the foreign 

 substances which the charcoal contains exert no decoloring 

 action, with the exception of sulphuretted hydrogen, and the 

 sulphurets under some circumstances only : if the foreign mat- 

 ters appear to have an influence in the decoloration, it is oc- 

 casioned by the development of surface merely in conse- 

 quence of the mixture. 



3. That no charcoal can discolor when it has been heated 

 so strongly as to become hard and brilliant ; that all its varieties 

 on the contrary enjoy this property, when they are sufficient- 

 ly divided, — not by mechanical action, but by the interposi- 

 tion of some substance which opposes their aggregation. 



4. That the superiority of animal charcoal, such as that 

 of blood, or gelatine, arises from its great porosity ; which 

 may be considerably increased by the effect of matter with 

 which it is calcined, such as potash. 



5. That potash is not Hmited in its effect of increasing 

 the porosity of the charcoal, by the abstraction of the for- 

 eign substances it may contain, but it acts on the char- 

 coal itself, in attenuating its molecules, and that by calcining 

 vegetable substances with potash, a decoloring charcoal may 

 be obtained ; add also by the calcination of vegetable, or an- 

 imal matters, with phosphate of lime or clay. 



6. That the decoloring force of different charcoals, ascer- 

 tained with respect to one substance, generally follows the 

 same order in all others ; but that the difierence between them 

 diminishes in proportion to the difficulty of decoloration in 

 the different liquids on which they are tried. 



7. That charcoal acts upon coloring materials by combi- 

 ning with them without decomposing them, as alumine would 

 do, and that, in some cases the color can be made alternately 

 to appear and disappear. 



8. The the following are the relative numerical forces of 

 tjie decoloring power of the charcoals employed, j^rsf, upon 



Vol. XVI.— No. 2. 23 



