208 



On the Densities of Carbonic Oxide, #c. 



son of the weight of nitrous oxide and of its contained nitrogen 

 might be of value. A suitable vessel would be filled, under known 

 conditions, with the nitrous oxide, which would then be submitted to 

 the action of a spiral of copper or iron wire rendered incandescent 

 by an electric current. When all the oxygen was removed, the 

 residual nitrogen would be measured, from which the ratio of equi- 

 valents could readily be deduced. The fact that the residual nitrogen 

 would possess nearly the same volume as the nitrous oxide from 

 which it was derived would present certain experimental advantages. 

 If indeed the atomic weights were really as 14 : 16, the ratio (x) of 

 volumes, after and before operations, would be given by 



2-2996 xx 14 



3-6359-^2996 xx 



, 7x3-6359 -. 



Whence X== 11 x 2-2996 = 1 QQ61 ' 



3*6359 and 2'2996 being the relative weights of nitrous oxide and 

 of nitrogen which (at 0° C. and at the pressure of the gauge) occupy 

 the same volume. The integral numbers for the atomic weights 

 would thus correspond to an expansion, after chemical reduction, of 

 about one-half per cent. 



But in practical operation the method lost most of its apparent 

 simplicity. It was found that copper became unmanageable at a 

 temperature sufficiently high for the purpose, and recourse was had 

 to iron. Coils of iron suitably prepared and supported could be 

 adequately heated by the current from a dynamo without twisting 

 hopelessly out of shape ; but the use of iron leads to fresh difficulties. 

 The emission of carbonic oxide from the iron heated in vacuum 

 continues for a very long time, ami the attempt to get rid of this gas 

 by preliminary treatment had to be abandoned. By final addition of 

 a small quantity of oxygen (obtained by heating some permanganate 

 of potash sealed up in one of the leading tubes) the CO could be 

 oxidised to C0 2 , and thus, along with any H 2 0, be absorbed by a 

 lump of potash placed beforehand in the working vessel. To get 

 rid of superfluous oxygen, a coil of incandescent copper had then to 

 be invoked, and thus the apparatus became rather complicated. 



It is believed that the difficulties thus far mentioned were over- 

 come, but nevertheless a satisfactory concordance in the final num- 

 bers was not attained. In the present position of the question no 

 results are of value which do not discriminate with certainty between 

 14*05 and 14*00. The obstacle appeared to lie in a tendency of the 

 nitrogen to pass to higher degrees of oxidation. On more than one 

 occasion mercury (which formed the movable boundary of an overflow 

 chamber) was observed to be attacked. Under these circumstances 



