t^% Effects of Animal Charcoal on Solutions* 



interference must be guarded against, as it may contribute, in 

 some cases, to increase the weight of precipitates. 



The animal charcoal, employed in the following experiments, 

 was prepared from common bone, or ivory black, by boiling 

 dilute muriatic acid upon it, and afterwards washing it with hot 

 water till the water came off tasteless. No more than ten or 

 twelve per cent, of charcoal remained after dissolving out the 

 earthy salts. On burning this charcoal, it left a grey ash, 

 amounting to about one-twelfth of the original weight, insoluble 

 in water and acids, and almost entirely silica. Charcoal, pre- 

 pared in this way, M. Bussy found to go no farther in disco- 

 louring than one and a half times its weight of the original 

 ivory black. 



In my first experiments, it was found that the prepared 

 charcoal, in great excess, had no sensible effect in impoverishing 

 a saturated solution of common salt at natural temperatures. 

 The proportion of salt remaining in solution was always as 

 great as water was found capable of retaining, at the same time, 

 at the lowest temperature which had occurred during the expe- 

 riment. 



A solution of nitrate of lead, with the charcoal repeatedly 

 agitated, and occasionally tested with carbonate of soda, gave 

 a distinct precipitate the first day, a much less distinct the 

 second, and the merest trace the third day. But, on heating 

 the water, the charcoal part of the nitrate was re-dissolved, 

 and afforded a copious precipitate, with carbonate of soda and 

 with sulphuretted hydrogen. 



The dinitrate of lead, which is soluble, was taken down 

 completely by the charcoal, so that no trace of it was perceived 

 by means of sulphuretted hydrogen. But on heating the water 

 over it to 200°, part was re-dissolved, as in the previous case, 

 but again taken down completely by the charcoal on cooling. 

 The action of the charcoal on the cold solution of the dinitrate 

 was immediate, and much more energetic than in the case 

 of the nitrate. The former salt, however, is much less 

 soluble in water than the latter. Other soluble subsalts were 

 tried. 



2. Three grains diacetate of lead in one ounce water, with 

 twenty grains common ivory black ; taken down completely, 

 and not re-dissolved in any degree on boiling. 



