of Organic Bodies. 15 



Method of examining the Inorganic Constituents of Oiganic 

 Substances. 



Vegetable substances are first freed as completely as possible 

 from all foreign admixtures ; solid animal matters are exposed 

 to a gentle heat, to remove the greater part of the water 

 they contain; and animal liquids are to be evaporated to 

 dryness at a gentle heat. In this state the substances are 

 placed in a Hessian crucible, the lid of which is furnished with 

 a hole in the middle, the joints between the lid and the crucible 

 are carefully luted with clay, and the crucible then placed for a 

 long time in a hot place, and, if possible, all the remaining mois- 

 ture expelled. It is then exposed to a moderately strong heat 

 in a wind-furnace in a charcoal fire; the gases which escape 

 through the hole are inflamed, and when the flame has burnt 

 out and no more gases are evolved, the hole is closed with an 

 accurate stopper of chalk, the crucible heated at a very low 

 red heat, and then allowed to cool with perfect exclusion of 

 the air. 



The examination of the carbonized mass resolves itself into 

 three parts. 



Part I. — The carbonized mass is first powdered as finely as 

 possible, then boiled for a long time with water in a platinum 

 dish, filtered and washed with hot water until a few drops of the 

 filtering liquid leave a slight residue only, when evaporated 

 upon platinum-foil. It is scarcely possible to continue washing 

 the mass until the liquid which runs through leaves no residue, 

 because a little phosphate of lime is always dissolved. It is 

 therefore best, when the residue obtained on evaporating the 

 water used in washing is very slight, to test a few drops ot the 

 water which runs through with solution of nitrate of silver ; 

 if a slight opacity only is produced, which disappears on the 

 addition of nitric acid, this arises from phosphate of lime in 

 solution, and we may be certain that all those constituents 

 which are soluble in water have been removed. If the tur- 

 bidity does not disappear on the addition of nitric acid, this 

 arises from the water used in washing still containing some 

 chlorides, and the washing must be continued longer. 



On boiling the carbonized organic substances with water, 

 as also on evaporating the aqueous extract, I have never been 

 able to detect the evolution of ammonia. Hence, during the 

 carbonization, neither alkaline cyanides nor alkaline cyanates 

 are formed. 



In all those substances which have hitherto been examined, 

 the aqueous solution contained chlorides. If the amount pre- 

 sent is small, the carbonized mass is easily washed ; but if they 



