488 REPORTS ON THE STATE OF SCIENCE. 



same reason flame is not propagated through a dried mixture of carbon 

 monoxide and oxygen. But, if steam be present, the interaction of 

 CO + OH 2 = C0 2 + H 2 would bring molecules of the dioxide into existence 

 with a much less degree of internal agitation, and therefore capable of 

 continued existence, whilst the hydrogen liberated would immediately 

 combine with oxygen, forming steam, which is less easily dissociated 

 than carbon dioxide. This explanation, whilst consistent with many of 

 the facts connected with the combustion of carbon monoxide, cannot be 

 extended to other well-known instances, and is particularly inapplicable 

 to the case of hydrogen. 



2. Mendelejeff, in his ' Principles of Chemistry,' ascribed the mutual 

 inertness of carbon monoxide and oxygen to the circumstance that gases 

 combine according to a supposed ' law of equal volumes,' or, in other 

 words, that from the kinetic standpoint the primary changes in all cases 

 must be considered as involving the collision of two molecules only. 

 In the case of carbon monoxide he postulated the following cycle of 

 changes : — 



(i) CO+OH 2 =C0 2 +H 2 ; (ii) H 2 +0 2 =H 2 2 ; (iii) CO+0 2 H. 2 =C0. 2 +OH 2 . 



But, according to this supposed ' law of equal volumes,' a well- 

 dried mixture of carbon monoxide and nitrous oxide, or of carbon 

 monoxide and ozone, should be active, whereas Dixon has proved them 

 to be as non-explosive as a dried mixture of the monoxide and oxygen. 



3. H. E. Armstrong has always contended that chemical actions 

 cannot occur between two perfectly pure substances, but require the 

 conjunction of an electrolyte in order to form a closed conducting 

 system. The presence of steam, which he supposes may always be 

 regarded as rendered ' conducting ' by association with some traces of 

 an electrolyte impurity, provides the necessary conditions for the 

 passage of the current, the oxygen playing the part of depolariser, 

 thus: — 



Before. After. 



CO OH 2 







I 

 O 



H 2 

 H>0 



CO OH 2 



OCO 

 OCO 



On the other hand, H. B. Dixon has urged that a rate of explosion of 

 nearly 1 , 700 metres per second for a moist mixture of carbon monoxide 

 and oxygen is incompatible with any interaction of the complexity thus 

 postulated. There is doubtless prima facie much force in this objection, 

 but it is by no means fatal, seeing that the dimensions of the explosion 

 wave are incomparably greater than molecular units, and the duration 

 of chemical action, though extremely short when measured in terms 

 of ordinary gross units of time, is at least many thousands of times 

 greater than the intervals between successive molecular collisions. 1 A 

 more serious objection to Armstrong's theory is the fact that there are 



1 As the writer understands Dixon's objection to Armstrong's view, it is that 

 whilst chemical action in the explosion wave may last a comparatively long time 

 (i.e., during many molecular collisions), and that therefore a quintuple molecular 

 collision might happen in that period, it is impossible for the wave to be propagated 

 as a sound-wave through quintuple collisions. Ordinary sound-waves may be many 

 molecules thick, but they are propagated through bi-molecular collisions. 



