SIR ANDREW NOBLE: RESEARCHES ON EXPLOSIVES. 207 



produced, and oxygen consumed, do not afford a means of distinguishing methane 

 from its homologues in presence of an excess of hydrogen ; thus ethane, together with 

 its own volume of hydrogen, would give the same numerical results as two volumes 

 of methane. A process of fractional combustion was therefore applied to some of the 

 samples obtained from high density charges, as these contained large proportions ot 

 saturated hydrocarbons. After removing carbon dioxide, carbon monoxide and 

 unsaturated hydrocarbons, an excess of oxygen was added and the hydrogen was 

 removed by repeatedly passing over gently heated palladinized asbestos contained in 

 a capillary tube attached to a pipette containing water, as in the ordinary Orsat- 

 Lunge apparatus, until no further decrease of volume occurred. The residual 

 mixture was then examined by explosion, &c., in the usual manner. In each case the 

 volume of carbon dioxide produced almost exactly half that of the decrease, 

 resulting from the explosion, which latter was equal to the volume of oxygen 

 consumed. These ratios agree with those required by the equation 



CH 4 +2O i = CO,+2H,0, 



but differ markedly from those which would result with the homologues of methane, 

 thus even with ethane the proportions are 4:5:7 instead of 1 : 2 : 2. It therefore 

 follows that the saturated hydrocarbons should be calculated as methane, none of the 

 other members of the series being present in appreciable quantities. Examination 

 of the water condensed in the closed vessel showed that the gas could not contain 

 either ammonia or cyanogen in marked quantities, as the distribution under high 

 pressure would so greatly favour the water. The presence of oxides of nitrogen is, 

 of course, incompatible with that of a large proportion of hydrogen, as the gases 

 have slowly cooled from a very high temperature. A trace of sulphuretted hydrogen, 

 sufficient to markedly discolour mercury, exists in the gas when black powder is 

 used as a lighter, but for all practical purposes the gaseous products of explosion 

 may be regarded as consisting entirely of carbon dioxide, carbon monoxide, hydrogen, 

 methane and nitrogen. 



One other arrangement of apparatus remains to be described, and that apparatus 

 is used both for determining the time that explosives of various forms and natures 

 require for their transformation, and for determining the rate at which they 

 communicate the heat accompanying the explosion to the walls of the vessel in which 

 the explosion takes place. 



The apparatus (see Plate 4) consists of an explosion vessel of the usual form, the 

 explosion vessel being closed at its two ends by gas-tight plugs, through one of 

 which pass the firing wires, while to the plug at the other end is fitted a pressure 

 indicator. 



The pressure indicator is provided with a steel plunger of small area, which is 

 exposed to the gas pressure. 



An enlarged continuation of this plunger engages the end of a spiral spring a, the 



