ON GASEOUS EXPLOSIONS. 269 
If the same quantity of the original CO, is made to pass the potash 
solution, and the residue is collected, this measures at the end of the 
same lapse of time 1°4 c.c., consisting of 
0.= 14, 
N 2= 86, 
which accounts for the small quantity of nitrogen in the products of 
dissociation of the CO. 
The ‘ Cold-Hot’ Tube.—In this arrangement the recombination 
of the dissociated gases is prevented by rapid cooling, instead of diffusion 
and dilution, as in the previous experiments. A thin brass tube, silvered 
externally, takes the place of the porous inner tube of the first appa- 
ratus. Through this is maintained a rapid and steady current of cold 
water. 
Experiments on CO.—A current of pure CO, made by the action of 
sulphuric acid on oxalic acid, is passed through the outer tube of the 
apparatus. The CO, in the CO is absorbed by passing through several 
wash-flasks of potash, then over a tube of iron, filled with red-hot iron 
wire, and finally more potash vessels. The exit-tube from the furnace 
passes to a baryta solution. As soon as the tube becomes red-hot, CO, 
is shown in the issuing products. Carbon deposits on the under side 
of the silver tube as soot. 
Modified ‘ Cold-Hot’ Tube.—The same arrangement as just de- 
scribed was modified by boring a hole about 0°2 mm. in diameter through 
the metal tube, and attaching to the outlet for the water a long glass 
tube bent vertically downwards. This acts like the old form of 
Bunsen pump, causing some gas to be drawn inwards at the hole, and 
to pass on with the current of water. The lower end of the water- 
delivery tube is bent so as to allow the gas issuing to be collected in an 
eudiometer. With this apparatus Deville considers he showed CO: to be 
‘ strongly dissociated at 1200° C.’ 
Sparking Experiments.—This is confirmed by a sparking experi- 
ment. 
If CO. confined over mercury in an eudiometer be sparked vigorously 
in presence of phosphorus, all the oxygen is absorbed as fast as pro- 
duced, and the dissociation is complete. 
Consideration of the papers, of which the above is an abstract, and 
also others not dealt with, has led me to believe that Deville may be 
more right as regards the magnitude of the dissociation produced in 
steam and CO: by heat than recent writers on the subject would lead us 
to suppose. Each experiment considered alone would not be unimpeach- 
able, but although there appear to be many pitfalls and possibilities for 
secondary effects to interfere with the reactions studied, yet the evidence 
seems so strong that it is hardly possible to discredit it. If this be the 
case, further work on the lines indicated by Grove and Deville, accom- 
panied by proper temperature measurements, would seem very desirable. 
For a repetition of the first experiment an external ‘ guard-tube,’ 
coming outside the glazed porcelain tube and conveying a stream of the 
gas to be studied, would be an obvious improvement. This would enable 
the effect of small leaks in the porcelain tube to be minimised. The 
glaze of the best Berlin tubes softens and is distinctly ‘tacky’ at 
1150° C., while after long exposure to 1200° C. the glaze sinks in and 
perishes. Silica tubes begin to sag, when unsupported in the hot parts, 
