350 CHARCOAL CARBON 



days. The dead parasites may be found in the faeces in 

 from sixteen to twenty hours after the administration of the 

 first dose. Occasionally a patient, after receiving carbon 

 bisulphide, shows symptoms of colic. This may be prevented 

 by walking the animal for an hour after giving the medicine. 



CHARCOAL-CARBON 



Two varieties of charcoal, or carbon, are used in medicine 

 and pharmacy wood charcoal, or carbo ligni, and animal 

 charcoal, or carbo animalis. The former is prepared by 

 piling billets of hard wood into heaps, covering them with 

 turf and sand, and leaving a few apertures for admission of 

 air. The pile is ignited : after the flame has risen through 

 the whole mass, the openings are closed, and combustion 

 proceeds slowly, without access of air. The high tempera- 

 ture dissipates moisture, breaks up the complex vegetable 

 matters into simpler forms, producing empyreumatic gases 

 and tarry fluids, and leaving a charred residue of about one- 

 fifth the weight of the original wood, and consisting of 

 chemically pure carbon and ash, with oxygen, hydrogen, 

 and traces of nitrogen retained in the porous mass. Oils or 

 resins, when burned in a deficiency of air, produce lamp 

 black a finely-divided, amorphous carbon. 



Animal charcoal, also known as bone or ivory black, is 

 chiefly prepared from bones, which are boiled to separate 

 fatty matters, and heated in close vessels until the ammonia- 

 cal gases cease to be disengaged. The fixed residue contains 

 about 10 per cent, of carbon, 88 per cent, of calcium phos- 

 phate and carbonate, and 2 per cent, of iron carbide and 

 silicide mineral matters which separate the carbon particles 

 and enhance their absorbent properties. 



Both vegetable and animal charcoal are remarkable for 

 their porosity, are brown-black, insoluble and inodorous, 

 readily absorb moisture, gases, and most vegetable colouring 

 matters. Animal charcoal is distinguished by its greater 

 density, its incombustibility, its bitter taste, its large propor- 

 tion of phosphates, and also by its greater absorbing power. 



ACTIONS AND USES. Charcoal is a desiccant, antiseptic, 

 disinfectant, and deodorant, and is used as a decoloriser in 



