APPENDIX. 545 



FOURTH GROUP. HYDROCARBONS. 



I. Pure gases. Pressures. 



attn. . 



(22) Acetylene, C 2 H 2 + O 5 15-29 



(23) Ethylene, C 2 H 4 + O 8 1613 



(24) Ethane, C 2 H fl + O 7 16-18 



(25) Methane, 2CH 4 -f O 8 16-34 



II. Varied mixtures.. 



(26) Ethylene and hydrogen, C 2 H 4 + H 2 + O 7 ... 14-27 



III. Gases containing oxygen. 



(27) Methylic ether, C 2 H 6 O + O 6 1991 



(28) Ordinary ether, C 4 H 10 O + O J2 16-33 



In regard to the relative rapidity of combustion of various deto- 

 nating gaseous mixtures, the authors found that in the total 

 combustion of hydrogen, carbonic oxide, cyanogen, and hydro- 

 carbons containing much hydrogen, by oxygen and nitrogen 

 monoxide, the rate of combustion was much slower with carbonic 

 oxide than with hydrogen. The use of nitrogen monoxide in place 

 of oxygen retarded the action, and the rapidity of combustion of 

 cyanogen and the hydrocarbons was little different from that of 

 hydrogen. 



In the case of incomplete combustion of cyanogen the rate was 

 more rapid than when the combustion was complete. 



Experiments on the influence of an excess of one of the com- 

 ponents, hydrogen or oxygen, showed that in both cases the com- 

 bustion was retarded, the retarding effect of the oxygen, however, 

 being nearly double that of the hydrogen for equal volumes. 



The presence of products of combustion also caused great 

 retardation, the rate being three times slower for an equal volume 

 of carbonic acid, and six times for carbonic oxide. An inert gas, 

 such as nitrogen, retards the combustion of hydrogen more than 

 that of carbonic oxide. This shows that the phenomenon is not 

 only due to the lowering of temperature, which is approximately 

 the same in both cases, but also to the greater inequality between 

 the velocities of translation of the gaseous molecules. 



Combustion proceeds more slowly in the less condensed isomeric 

 systems. 



When two combustible gases, such as hydrogen and carbonic 

 oxide, are burned with oxygen, the rate is in no case the mean of 

 that of the two gases. They appear to burn separately, each with 

 its own rapidity. 



The fact that the rapidity of combustion of hydrocarbons rich 

 in hydrogen is nearly the same as that of hydrogen appears to 

 indicate that the hydrogen burns before the carbon, even in total 

 combustions. 



From their experiments on the influence of the density of 

 detonating gaseous mixtures on the pressure the authors find that 

 the results do not differ much from those calculated according 

 to the ordinary laws of gases, but have the advantage of being 

 independent of the laws themselves. They conclude that at 



2N 



