114 Odier on the Chemical composition 



fectly dry amianthus, in the admirable apparatus invented by Mr. 

 Cooper, employing at first a very gentle heat, and gradually raising 

 it until the part of the tube containing the carapace was bright red 

 hot throughout, and gas ceased to come over. The tube was then 

 carefully weighed in a very delicate balance, the water expelled 

 by heat, and the tube weighed again. The loss of weight (de- 

 ducting that of the hygrometrical water previously ascertained as 

 stated above) gave the quantity of water formed, and consequently 

 that of the hydrogen in the carapace. The exact volume of gas 

 at 60° produced by the combustion was next ascertained, and the 

 carbonic acid absorbed by caustic potassa, the volume of which 

 gave the weight of the carbon, and that of the residual gas, after 

 allowing for the atmospheric air in the vacant part of the tube, 

 gave in like manner the weight of the nitrogen, its real nature not 

 being taken for granted, but in every case ascertained by direct 

 experiment. The difference of weight of the sum of these ele- 

 ments, and the quantity of carapace employed, is assumed to de- 

 note the weight of the oxygen. I made many experiments in this 

 manner, both with peroxide, and protoxide of copper, but to 

 avoid prolixity, I shall give the results of the two last only, made 

 with the protoxide, premising that in all nitrogen was constantly 

 obtained, and in pretty uniform proportion. 



Exp. 1. Three grains of carapace, the necessary deductions 

 being made for hygrometrical water and incombustible matter, 

 were found to be equivalent to 2-072 grains of pure dry carapace, 

 and gave, by the mode of operating described above — 



Grs. Grs. 



Carbon 0-962 or per cent. 46'43 



Hydrogen 0-129 6-22 



Nitrogen 0-239 11-05 



Oxygen 0-742 35-81 



2-072 99-51 



Exp. 2. 4-75 grains of the same carapace, equivalent to 3-28 

 grains in. a dry and pure stale gave — 



