1824.] Mr. Gray's Reply to the Editor. 127 



into two classes, according to the greater or less use they make 

 of analogical reasoning in their theories. Formerly from the 

 want of a sufficient number of facts, analogical reasoning was 

 the sole basis of chemical theory as may be seen in Beccher ; 

 by degrees direct evidence has been obtained on certain points, 

 but not yet on all. Berzelius and some others, among which, 

 did not my habitual indifferentism hinder me, I should rank, are 

 of opinion, that the analogical reasoning of our forefathers 

 should be retained so long as the facts which come to light can 

 possibly be explained by their hypotheses, and even in case this 

 can no longer be done, we should make as little change as possi- 

 ble. These are the chemists I have denominated rationals, not 

 from any superiority in understanding which they may claim, 

 but from their greater use of analogical reasoning than is 

 allowed by the opposite class ; analogical and rational being 

 constantly used in science as synonymous ; and the latter word 

 being best adapted to be used as a substantive. The peculiar 

 dogma of the other school is to reject all analogical reasoning, 

 and consider every body which has not yet been separated into 

 others as simple. To these chemists, which include the generality 

 of modern professors and authors, 1 have given not the name of 

 irrationals as you state, and which 1 expressly avoided lest I 

 should unintentionally offend, but that of Epicureans ; because 

 Rouelle, who may be considered as the father of the sect, is said 

 to have inscribed on the walls of his lecture room, a saying 

 ascribed to Epicurus ; That we can know only what we perceive 

 by our senses. 



No man has a higher respect for Sir Humphry Davy, as a 

 chemist, than myself. Of his two precursors in the same path, 

 Homberg and Scheele, it is only the latter that can enter into 

 any competition with him; and if the Pomeranian exceeds in the 

 number of new substances he has discovered, the Englishman 

 has by far the advantage in the greater practical advantages to 

 be derived from his labours. 



As to my opinion, however, of Lavoisier, which I have defer- 

 red to this place, it is unaltered by your remarks. He indeed 

 turned chemistry upside down, and he has shown us that the 

 phenomena of chemistry may be explained by thus reversing its 

 former theory, but theories are such tottering things that I do 

 not consider this as any great feat. I still deny that chemistry 

 is deeply indebted to him, in any other way than that the total 

 change he proposed, coinciding with the political circumstances 

 of the times, was brought into more notice than it would other- 

 wise have obtained, and thus it became necessary for the culti- 

 vators of chemistry either to defend the old doctrines, or 

 advocate the new : and in this manner indeed he has indirectly 

 been of the greatest service to it. How often are his experi- 

 ments referred to? Seldom: — I might say never. Are they 

 considered as examples of the most scrupulous accuracy like 



