A text-book on chemistryFor the use of schools and colleges . urnings must bekept at a red heat while the actual combustion is inprogress. Instead of the analysis being terminated bydrawing air through the apparatus, the remaining partof the bicarbonate is decomposed, so that the residueof nitrogen may be expelled by carbonic acid. The nitrogen is collected by the aid of the tube a,Fig. 297, in a graduated cylinder over mercury, the cyl-inder containing enough solution of caustic p6tassa toabsorb the carbonic acid that comes over. In determining nitrogen as ammonia by the methodof Varrentrapp
A text-book on chemistryFor the use of schools and colleges . urnings must bekept at a red heat while the actual combustion is inprogress. Instead of the analysis being terminated bydrawing air through the apparatus, the remaining partof the bicarbonate is decomposed, so that the residueof nitrogen may be expelled by carbonic acid. The nitrogen is collected by the aid of the tube a,Fig. 297, in a graduated cylinder over mercury, the cyl-inder containing enough solution of caustic p6tassa toabsorb the carbonic acid that comes over. In determining nitrogen as ammonia by the methodof Varrentrapp and Will, the nitrogen is converted intoammonia by igniting the compound containing it withsoda-lime, a mixture of caustic soda, 1, and caustic lime2 parts. The soda-lime furnishes hydrogen from itswater to the nitrogen, forming ammonia; the oxygenof the water unites with the carbon of the organic ammonia is passed through a Varrentrapp andWills bulbs, partly filled with hydrochloric acid of aspecific gravity of , a, Fig. 298. The tube d serves. to connect it with the combustion-tube a in the furnaceg. By treating the contents of the bulb apparatus withbichloride of platinum the double chloride of platinumand ammonia is formed, and may be, after evaporationto dryness and washing with ether and alcohol, collect-ed on a filter and weighed. Sulphur compounds are oxidized as stated in the be-ginning of this lecture, and weighed as % sulphate of How is the nitrogen collected ? How may the nitrogen be con-verted into ammonia ? Describe the determination of nitrogen asfree ammonia. How are sulphur and chlorine determined ? 390 DIALYSIS. baryta. Chlorine is determined as chloride of silver,the substance being ignited with soda-lime, the massdissolved in dilute nitric acid, and precipitated with ni-trate of silver. A process of analysis has been invented by Grahamcalled Dialysis, in which the principles of liquid diffu-sion ar& brought into use. He divides all substancesint
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