3(3 -Dr. Q. Grore on a Method of Measuring 



weak ones. 3rd. The losses were often largest with the sub- 

 stances of greatest chemical energy, though several striking 

 exceptions exist to this statement. Whilst they were usually 

 larger with hydrochloric than with hydriodic acid, and with 

 sulphuric than with nitric, chloric, carbonic, and the halogen 

 acids, they were greater with formic acid than with either of 

 these ; and whilst they were larger with aluminium than with 

 tin as a positive metal, they were usually larger with tin than 

 with cadmium, and with cadmium than with zinc or mag- 

 nesium. A reasonable explanation of the more feeble energy 

 of union, and consequently smaller loss of energy, during the 

 act of union of stronger substances than with weaker ones in 

 certain cases is, that the energy of action and amount of loss 

 depend upon the mutual relations of the inherent molecular 

 motions of each of the two substances ; that when these are 

 so related that they cannot coexist, but must freely neutralize 

 each other, the loss of energy is the greatest. The incom- 

 patible motions of carbon and oxygen, and the compatible 

 ones of carbon and chlorine, at a red heat are familiar 

 examples. 4th. The order of magnitude of loss of electro- 

 motive force was in the majority of cases substantially the 

 same with different positive metals. 5th. In nearly all the 

 cases in which thermochemical data are given, the loss of 

 electromotive force varied directly as that of chemical heat, 

 as if the two forms of energy were concomitant effects of the 

 same cause, viz. decrease of molecular motion. And, 6th. 

 The amount of loss did not vary regularly with the atomic 

 weights. As the amounts of loss of electromotive force 

 depend in every case upon each of the two uniting substances 

 and upon the relations of their molecular motions to each 

 other, it is not probable that they would vary regularly with 

 the magnitude of the atomic weight of the positive ingredient 

 alone in its chemical series, or with that of the negative one 

 alone in its series, but would be affected by both. The general 

 relations of the amounts of electromotive force of the in- 

 gredients and of their compounds in the various groups to the 

 atomic weights of the substances, when measured by different 

 positive metals, have already been partly examined (see Proc. 

 Birnu Phil. Soc. 1891, vol. vii. p. 253). By arranging the 

 series in each group in the order of the halogen acids, the 

 agreement with the atomic weights was less conspicuous than 

 when the order was that of the alkali metals. 



The next section, " B," relates to the Formation of Salts 

 from Acids and Carbonates, and gives in each instance the 

 separate amounts of the electromotive force of the acid, of the 

 carbonate, and of the salt produced by them, also the calcu- 



