246 § 125. ANALYSIS OF ASHES. 



In this acid solution precipitate sulphuric acid with baric 

 acetate, and chlorine with argentic nitrate in the filtrate 

 from the baric sulphate ; treat this last precipitate as one 

 produced in the presence of organic matter, if it is at all 

 abundant. 



125. The following method of incineration and analysis 

 is given by Reichhardt, by which the volatilization of any 

 mineral matters is avoided, as well as the addition of any- 

 thing to the ash to facilitate incineration. 



1. Carefully char enough of the dried substance to yield 

 2 grms. of ash, pulverize the coal, and exhaust it with 

 several portions of hot water. 



a. Add argentic nitrate to this extract immediately. 



h. Exhaust the coal with water containing a little nitric 

 acid, wash with the same, and add this extract to a. 



2. Incinerate the coal completely, and exhaust the ash, 

 first with water, and then with moderately concentrated 

 nitric acid, and add these extracts to those obtained in 1. 



3. Determination of sulphur and chlorine. — The pre- 

 cipitate by argentic nitrate, in these extracts, contains the 

 sulphur that was present in a soluble form in the plant, 

 and the chlorine. Acidify the mixture of precipitate and 

 liquid with nitric acid, if not already acid, collect the 

 precipitate of argentic sulphide and chloride on a dried and 

 weighed filter, wash it well, and add the filtrate and wash- 

 ings to those obtained in 4, below.' 



Treat the precipitate on the filter with ammonia, by 

 w^hich tlie argentic chloride is dissolved, wash the insolu- 

 ble argentic sulphide, dry it at 100°, and weigh. It con- 

 tains 12.9*^1 of sulphur. 



Precipitate argentic chloride in the ammonic extract, by 

 nitric acid in excess, and treat the precipitate in the usual 

 manner (§ 63). 



4. Heat the residue, insoluble in nitric acid in 2, with 



