124 Effects of Animal Charcoal on Solutions, 



in caustic potash, which was diluted with water till it amounted 

 to three ounces. Twenty grains of the charcoal, added to the 

 above solution, in a phial, which was then corked up, took 

 down so much of the oxide of lead that the white colour of the 

 latter substance was quite discernible among the charcoal. 

 Here we have the colour of the charcoal disguised in the com- 

 pound. Making successive additions of charcoal, the oxide of 

 lead in solution was reduced to a trace by ninety grains; the 

 last additions of charcoal floated over the heavy portion con- 

 taining the oxide of lead ; the supernatant solution, which had 

 a greenish tinge, was poured off, and the charcoal washed, 

 thrown on a filter, and dried at a heat which did not exceed 

 212°. When dry, innumerable metallic particles were visible 

 in it ; so that the oxide of lead is easily reducible by the char- 

 coal attached to it. 



The oxide of zinc was withdrawn entirely by the charcoal 

 from solution in caustic ammonia. 



A deep-red solution was made of five grains iodine in fifteen 

 grains pure hydriodate of potash, dissolved in two ounces 

 Avater. Forty grains of the charcoal were added before the 

 colour of the iodine was wholly removed from the solution ; the 

 liquid acquired a faint acid reaction ; the carbon was washed, 

 and dried in a filter on the sandbath without exhaling any 

 iodine vapours ; but on heating it strongly in a flask by a lamp, 

 iodine rose in vapour, and condensed on the sides of the flask 

 with some moisture. The iodine was afterwards re-absorbed 

 by the dry charcoal when cold. 



Labarraque's disinfecting fluid (chloride of soda with bicar- 

 bonate of soda) may be boiled without being materiafly injured; 

 but I was surprised to find that ebullition for a few seconds of 

 a large quantity of that fluid, in contact with a few grains of 

 the charcoal, completely destroyed its bleaching power. 



The same effect took place in the cold, on agitating the fluid 

 and the charcoal together for a few minutes. No gas was 

 emitted in either case. On evaporating the saline solution to 

 dryness, it was found to contain no notable quantity of chlorate 

 of soda. Twenty grains of carbon were adequate to destroy 

 the bleaching power of a pint of the disinfecting fluid recently 

 prepared. 



A solution of common bleaching powder, chloride of lime, 



