306 PRINCIPLES OF CHEMISTRY 



Thus a whole series of phenomena show that the chemical reaction 

 of substances actually takes place, as a rule, between equal volumes, 

 but this does not remove the possibility of the frequent reaction of un- 

 equal volumes, although, in this case, it is often possible to discover a 

 preceding reaction between equal volumes. 11 



the presence of traces of water in many reactions, as, for instance, in the explosion of 

 carbonic oxide with oxygen, and perhaps the very theory of the explosion of detonating 

 gas and of the combustion of hydrogen gain in clearness and truth if we take into con- 

 sideration the preliminary formation of hydrogen peroxide and its decomposition. We 

 may here point out the fact that Ettingen (at Dorpat, 1888) observed the existence of 

 currents and waves in the explosion of detonating gas by taking photographs, which 

 showed the periods of combustion and the waves of explosion, which should be taken into 

 consideration in the theory of this subject. As the formation of H. 2 O 2 from O 2 and H 2 

 corresponds with a less amount of heat than the formation of water from H 2 and O, it 

 may be that the temperature of the flame of detonating gas depends on the pre-formation 

 of hydrogen peroxide. 



11 The possibility of reactions between unequal volumes, notwithstanding the general 

 application of the law of Avogadro-Gerhardt, may, in addition to what has been said 

 above, depend on the fact that the participating substances, at the moment of reaction, 

 undergo a preliminary modification, decomposition, isomeric (polymeric) transformation,. 

 &c. Thus, if NO 2 seems to proceed from NoOj, if O 2 is formed from Og, and the converse, 

 then it cannot be denied that the production of molecules containing only one atom is 

 also possible for instance, of oxygen as also of higher polymeric forms as the 

 molecule N from N 2 , or H 3 from H. 2 . In this manner it is naturally possible, by means of a 

 series of hypotheses, to explain the cases of the formation of ammonia, NH 5 from 3 vols, 

 of hydrogen and 1 vol. of nitrogen. But it must be observed that perhaps our 

 information in similar instances is, as yet, far from being complete. If the existence of 

 hydrazine or diamide N 2 H 4 (Chap. VI. Note 6) be verified, then, perhaps, an amide NoH.> 

 will be discovered [this substance is now stated to'have been obtained] in which 2 vols. 

 of hydrogen are combined with 2 vols. of nitrogen that is, the reaction is accom- 

 plished between equal volumes. If it be shown that diamide gives nitrogen and 

 ammonia (3N 2 H4 = N 2 + 4NH 3 ) under the action of sparks, heat, or the silent discharge r 

 <fec., then it will be possible to admit that it is formed before ammonia. And, perhaps, 

 the still less stable amide N 2 H 2 , which may also decompose with the formation of 

 ammonia, is produced before the amide N 2 H 4 . 



I mention this to show that the fact of there being apparent exceptions to the law of re- 

 actions between equal volumes does not prove the impossibility of their being included under 

 the law on further study of the subject. Having admitted a certain law or hypothesis, then 

 consequences must be deduced from it, and if by their means a clearness and harmony 

 is arrived at and all the more, if by their means that which could not otherwise be 

 known can be recognised then the consequences verify the hypothesis. This was the case 

 with the law now under discussion. The simplicity alone of the deduction of the weight 

 proper to the atoms of the elements, or the fact alone that having admitted the law it 

 follows, as will afterwards be shown, that the vis viva of the molecules of all gases 

 is a constant quantity, is alone a sufficient reason for retaining the hypothesis 

 if not for believing in it as a fact beyond doubt. And as by the acceptance 

 of the law it became possible to foretell even the properties and atomic weights of 

 elements which had not yet been discovered, and as these predictions afterwards proved 

 to be in agreement with the actual facts, it is evident that the law of Avogadro-Gerhardt 

 penetrates deeply into the nature of the chemical relation of substances. This being 

 granted, it is possible at the present time to expound and deduce the truth under 

 consideration in many ways, and in every case it, like all that is highest in science (for 

 example, the law of the indestructibility of matter, the law of the conservation of energy.. 



