S72 Intelligence and Miscellaneous Articles. 



the latter, are present oiilj- Avhen too high a temperature has been 

 employed in the charring. From tiiis however it is evident that the 

 nature of the salts in the aqueous extract may vary somewhat, ac- 

 cording to the temperature employed and the longer or shorter 

 digestion of the mass with water. When the charring is effected at 

 too high a temperature, tlie greater portion of the carbonated alka- 

 lies are decomposed by the earthy phosphates. 



The accurate examination of the salts in the aqueous extract is 

 not accompanied with any great difficulties. One circumstance 

 however renders it somewhat less easy ; carbonate and phosphate of 

 lime and magnesia frequently dissolve to a considerable extent in 

 neutral solutions of alkaline salts, particularly of alkaline carbonates 

 and phosphates ; in the course of time tiiey are deposited from the 

 solutions, especially after the application of heat. When therefore 

 the aqueous extract is eva]>orated, it frequently becomes somewhat 

 turbid, and deposits small quantities of earthy salts. It should con- 

 sequently be evaporated nearly to dryness, diluted with water, and 

 the solution set aside for some time; v.'hen the earthy salts have 

 subsided, it is filtered, the filtered solution evaporated to dryness, 

 and its weight determined. When there is no alkaline phospliate or 

 sulphate present, the examination is very easy. The quantity of 

 carbonic acid is determined in a suitable apparatus by decomposition 

 with nitric acid ; and upon this that of die chlorine by a solution of 

 silver ; upon which, after removing the oxide of silver by hydro- 

 chloric acid and concentrating the liquid, the potash may be sepa- 

 rated from the soda by chloride of platinum. With tiie presence of 

 alkaline sulphate or phosphate, it is advisable to divide the quantity 

 of the alkaline salts, and in the one half to determine the quantity 

 of the chlorine and the alkalies, and in tlie other that of the carbonic 

 acid by decomposition with hydrochloric acid ; tiiat of tlie sulphuric 

 acid by a salt of barytcs ; and after removing the baryta by means 

 of sulphuric acid, and supersaturating with ammonia, to ascertain the 

 quantity of phosphoric acid by means of a solution of a salt of mag- 

 nesia to which cliloride of ammonium has been added. 



The charred mass, exhausted with water, is now digested with hot 

 hydrochloric acid for some length of time, and tiieii wasiied with 

 water. This operation requires considerably more time and water 

 than in the treatment of the charred mass with water; and if the 

 washing were to be continued until some drops of the filtered liquid 

 no longer produced any opalescence in a solution of silver, an enor- 

 mous length of time, several months, would be required, especially 

 in operating upon large quantities. The edulcoration therefore is 

 only continued until a considerable quantity of the wash-water does 

 not exhibit a traee of precipitate when treated with ammonia; it 

 will then also be seen that a large quantity of the wash water, when 

 evaporated upon platinum, no longer leaves any perceptible residue: 

 this does not require mucli time, especially when hot M'ater is used. 



The acid solution contains the earthy phosphates which existed 

 as such in the organic substance and the peroxide of iron. It is 

 precipitated by ammonia, and after having determined the weight 



