258 Determination of Nitrogen in Organic Compounds. 



dering a complete washing difficult. Seldom is more than an 

 ounce to an ounce and a half of fluid needed for the removal of 

 all the hydrochlorate of ammonia." 



" To this fluid, now containing hydrochlorate of ammonia, an 

 excess of a pure solution of the chloride of platinum is added, 

 and it is then evaporated to dryness, either first by the aid of a 

 spirit and then by a water bath, or entirely by the latter means. 

 From a well conducted burning, the chloride of platinum and 

 ammonia that is obtained, is always beautifully yellow ; but if 

 the material contained a great deal of carbon, or was burnt with 

 difficulty, then the chloride of platinum and ammonia is of a 

 darker color. This color though, has little or no effect upon the 

 accuracy of the result, supposing the washing to have been care- 

 fully done." 



" Upon the residue in the porcelain capsule, after it has cooled, 

 a mixture of two parts of absolute alcohol and one of ether is 

 poured. This dissolves the excess of the chloride of platinum, 

 and no part of the chloride of platinum and ammonia. It is 

 immediately known, whether there has been an excess of the 

 chloride of platinum, by the fluid assuming a yellow color ; if it 

 is colorless, then there has been a deficiency." 



" The washing of the residue is performed easiest by holding 

 the capsule, after the fluid has been poured upon a weighed filter, 

 perpendicularly over the same, and washing the precipitate in, 

 with the solution of alcohol and ether. The filter m^ust be 

 washed by the same mixture until it passes without color or acid 

 reaction. The precipitate and filter are dried on a covered cap- 

 sule or weighed tube at 212'^ Fah. and weighed. It is well, 

 in order to continue the result, to decompose the chloride of pla- 

 tinum and ammonia by heat, and out of the residue obtained, 

 calculate again the quantity of nitrogen, and if the chloride of 

 platinum was pure, the quantity of nitrogen calculated by this 

 latter method will not diff"er from the double chloride." 



In decomposing the chloride of platinum and ammonia, it must 

 be done by heating it, enveloped in its filter, gradually to redness ; 

 for if it be done too hastily, the vapor of the muriate of ammo- 

 nia and chlorine will remove mechanically some of the platinum. 

 The chloride of platinum used in this process, must be perfectly 

 pure, and Drs. V. and W. state, that it is difficult to obtain spongy 

 platinum without a trace of muriate of ammonia, by simply de- 



