220 Notices of the Labours of Continental Chemists. 



ploy more than 400 milligrammes with substances containing 

 little nitrogen, and not less than 200 milligrammes of those 

 which contain much. The weighed quantity of the sub- 

 stance is mixed with the measured quantity of soda-lime in a 

 mortar previously somewhat 'inarmed and unglazed, by stirring 

 goitly with the pestle. If these two measures of precaution 

 are observed, there is no danger of any loss resulting from 

 an adhesion of substance to the sides of the mortar and pestle. 

 When the mixture has been introduced into the tube in the 

 usual manner, the mortar is repeatedly rinsed with some 

 soda-lime, the tube filled within an inch of tlie aperture, and 

 a close layer of previously ignited asbestos introduced to pre- 

 vent any of the fine powder being carried away by the gases 

 evolved during the burning, which, especially on employing 

 a mixture of the hydrate of potash and lime, would give rise 

 to incorrect results, as the potash-chloride of platinum acts 

 in the same way towards solvents as the ammonio-chloride. 

 In this respect the mixture of soda and lime is preferable, for 

 should any such accident happen, the soluble soda- chloride 

 of platinum is easily removed by washing. 



The tube is then connected with the apparatus containing 

 the muriatic acid by a soft tight-fitting cork, placed in a com- 

 mon combustion furnace, and some air expelled by warming 

 the bulb a with a glowing charcoal, to see whether the appa- 

 ratus be air-tight ; if so, the front part of the tube, which con- 

 tains none of the organic substance, is heated to redness by 

 surrounding it with glowing charcoal, that nothing may distil 

 over undecomposed. The cork must be kept as warm as pos- 

 sible, that it may not retain or imbibe any moisture, which, 

 b}' absorbing ammonia, would occasion an error in the result. 

 As soon as this part of the tube is red-hot the burning is pro- 

 ceeded with ; carbonic acid is formed from the oxygen ot the 

 hydrate and the whole or a part of the carbon of the sub- 

 stance ; the hydrogen set free combines with the nitrogen in 

 its nascent state as ammonia, which escapes in the form of 

 gas. At the same time, according to the amount of carbon 

 in the substance, pure hydrogen, or carburetted hydrogen 

 gas, is given off, which are not absorbed by the acid, and in- 

 dicate the progress of the combustion. It is particularly ob- 

 served, that the burning must be carried on so quickly that a 

 constant and uninterrupted evolution of gas takes place; there 

 is no danger of any ammoniacal gas escaping; the absorption 

 is so complete and rapid that there is rather reason to fear the 

 acid rising into the tube, which would render the analysis use- 

 less. Only few substances contain so much nitrogen that the 

 whole carbon requires to be oxidized and converted into car- 



