136 SPECIAL METHODS OF ANALYSIS. 



suspend it in water through which a current of 

 sulphuretted hydrogen is passed, filter, evaporate 

 the filtrate to dryness on the water-bath, and heat 

 the residue, supposed to be malic acid ; maleic 

 acid should be fiormed (§ 73). - - - - B. 



B. 



DETECTION OF THE BASIC ELEMENTS. 



1. a. The substance is a solution, or it is soluble in 

 water, or dilute or concentrated hydrochloric or 

 nitric acid. This solution will be referred to as 



WiQ first solution. - 3 



h. Not soluble, or only partially soluble ; separate 

 the soluble from the insoluble part by filtration ; 

 this filtrate will be referred to as the first solution. 2 



2. This insoluble substance was found, in the exami- 

 nation for acids, to consist entirely of carbon, - S 

 Not. Dry it, mix it intimately with four parts of 

 potassic and sodic carbonate, and a little sodic ni- 

 trate, fuse the mixture 10-20 minutes on platinum 

 foil, and exhaust the fused mass with hot water ; 

 decant ofi* this aqueous extract^ wash the residue 

 once or twice by decantation, then treat it with 

 very dilate hydrochloric acid, and evaporate the 

 mixture to dryness ; moisten this second residue 

 with concentrated hydrochloric acid, and, after a 

 Avhile, add water, heat, and finally separate this 

 acid solution from the insoluble silica, by filtra- 

 tion. 



Acidify the aqueous extract of the fused mass, ob- 

 tained above, with hydrochloric acid, and test a 

 small portion of it for sulphuric acid with baric 

 chloride ; if a fine white precipitate is formed, and 

 lead or barium is subsequently found among the 



