in Magnetism and Electric?///. 115 



the various notions which have up to the present time been held 

 on the nature of water, it is highly important that a proper esti- 

 mate should be taken of the powerful influence which the chro- 

 nological order in which some discoveries in physical science are 

 made has in establishing in the minds of philosophers of one 

 generation ideas of causation and composition which are looked 

 upon as absurd by philosophers of another. Thus we find that 

 water, up to the time of Cavendish and Watt*, was considered to 

 be an element, simply on account of the inability of chemists to 

 convert it into anything else ; while the present notion of the 

 compound nature of water rests entirely on the inability of mo- 

 dern chemists to obtain water from oxygen or hydrogen alone, 

 or to obtain either of these gases alone from water. 



223. Now, had the chronological order in which the experi- 

 ments described in this paper and those of Cavendish and Watt 

 were made been reversed, the doctrine of the transmutable na- 

 ture of water would at once have been accepted, as agreeing 

 strictly with observation and experiment. But the theory of the 

 atomic composition of water, if broached for the first time at the 

 present day, would be summarily rejected as not accounting 

 either for the evolution of oxygen or hydrogen from water form- 

 ing part of the terraqueous globe (200, 201), or for the recon- 

 version of either of these gases alone into water (216, 217). 



224. Nor would the theory of Grothuss under these altered 

 circu.m stances meet with any better reception at the present day 

 than would be accorded to the theory of the composition of water, 

 because the former theory, as we have seen, breaks down com- 

 pletely when called upon to account for the electrolyzation of pla- 

 netary masses of water by means of a single electrode, or when 

 the distance between the two electrodes is considerable ; and yet, 

 although the theory of Grothuss was invented solely for the 

 purpose of reconciling the phenomenon of the electrolyzation of 

 water with the theory of its composition f, and therefore ought uot 

 to be used in any manner to support the latter theory, there will 

 not be found wanting some minds in which these two theories 

 are so confusedly mixed together that Grothuss's theory will be 

 brought forward to explain and support the theory of the com- 

 position of water, while the latter theory will, in its turn, be 

 adduced as proof sufficient of the truth of the theory of Grothuss. 



225. It is to philosophers of a breadth and liberality of mind 

 sufficient to realize the full force of the accidental influences 

 which I have just indicated that I look for an impartial conside- 

 ration of this great question — to philosophers who are so far 



* Philosophical Transactions, 17S4, pp. 130, 329. 



t " Theorie de la decomposition des liqnides par l'electricite galva- 

 Dtque," par C. J. D. de Grothuss. Annates de Chimie, vol. Iviii. p. 64 (1806), 



I 2 



