32 Mr. Rij^g on a Method of analysing Organic Compounds, 



an inch or more of the same kind of oxide : the tube is then 

 filled up with from fifteen to twenty-five grains of dry amian- 

 thus, and which, during the process of decomposition, con- 

 denses tlie vapour of water, and dries the gaseous products. 

 The part of the tu])e which includes the amianthus is then 

 heated, so as to drive off all moisture and decomposable mat- 

 ter that may be combined with it, and allowed to cool, when 

 it is weighed, and attached lo the bent tube by the collar, as 

 shown in the diagram. The bent tube is placed in the mer- 

 curial trough, and the analysing tube rests on the frame or 

 cradle, made of two pieces of strong wire bent at both ends at 

 right angles, and connected together in an oblique direction 

 by slender wires, as represented in the subjoined diagram. 



A spirit lamp upon the principle invented by Mr. Cooper, and 

 which can at pleasure be made to give off a flame from one to 

 six, or from one to ten inches in length, and about six inches 

 in height, is what I use. A flame, about an inch in length, is 

 first applied to that part of the tube where no organic com- 

 pound lies ; so soon as this part of the oxide is brought to a 

 red heat, the flame is gradually but very slowly increased in 

 length, until all that part of the tube, where the compound and 

 black oxide are, is at a white heat. During this period the 

 tube is turned round in the flame, the caoutchouc collar ad- 

 mitting of this being done at pleasure. At no time is the de- 

 composition of the substance under analysis quick, but, on the 

 contrary, very slow. The ignited part of the tube being kept 

 at a high temperature, we insure perfect combustion, and pre- 

 vent the formation of carbonic oxide, which is in all proba- 

 bility the source of much error in quick processes. 



During the latter part of the process, and when it is certain 

 that all the atmospheric air has been expelled, a portion of 

 the gaseous products is collected in a separate small tube gra- 

 duated to hundredths of a cubic inch. When no more gas 

 passes over, the flame is extinguished, and the contents of the 

 tube are shifted by raising and lowering it with a view to that 

 end, and without removing the bent tube from the mercurial 

 trough. The whole being arranged again as at the commence- 

 ment, that part of the tube which contained the compound 

 under analysis is submitted to a higher temperature, if pos- 

 sible, than before. 



The analysing tube is now detached from the other, al- 

 lowed to cool, and weighed, and the weight lost is found to be 



