236 Scientific Labors and Character of 



the water that appeared ; and it seemed decisive in favor of this con-, 

 elusion, that the quantity of oxygen contained in the water, was ex- 

 actly that which existed in the oxide of tin. This last fact left a strong 

 impression in favor of Davy's hypothesis, and against the idea sup- 

 ported by Murray, that tlie water present was the same as had before 

 existed in the muriatic acid, and which was released when the acid 

 went into combination with the base. But the doctrine of equivalent 

 quantities has proved, that the quantity of oxygen which is contained 

 in the water produced in this experiment, would be precisely the 

 same, whether derived from the oxide or the acid.* 



In this manner did the controversy proceed, each successive paper 

 producing arguments which seemed invincible in favor of the writer 

 and against his antagonist, while every thrust was parried with the 

 dexterity of the most accomplished masters. Nor did it seem pos- 

 sible to settle the question, until the discovery of iodine so much 

 strengthened the hypothesis of Davy, that almost every chemist of 

 the age from that period has adopted it. 



It has been said of Sir Isaac Newton, that he was so well acquaint- 

 ed with nature and understood her analogies so fully, that he always 

 guessed right. The increasing probability which has followed many of 

 the novel hints and suggestions thrown out by our philosopher, at a very 

 early period, (for example those respecting the identity of chemical 

 and electrical attractions, the geological agencies of the metallic bases 

 of the earths and alkalies, and the simple nature of chlorine,) almost 

 persuades us to apply to Sir Humphry Davy a similar remark. 



It is hardly possible to review the history of the foregoing contro- 

 versy, without being strongly impressed with the delusive nature of 

 hypotheses in general, if by hypothesis we understand a supposition 

 of which there is no other proof, than that it explains all the phenom- 

 ena to which it is applied. The two hypotheses of electricity as well 

 as those respecting oxy-muriatic acid, applying as they respectively 

 do to a great multitude of facts, while we know that one or the other 

 of them must be false, prove the danger of relying on such a con- 

 formity of our supposition with facts, as a criterion of their truth. 



In the year 1812, at the age of 32, Davy stood on one of the 

 proudest heights of science. By his extraordinary discoveries he 

 had extended the empire of man over matter ; by strong powers 

 of reasoning united with great ingenuity of research, he had changed 



* Murray's Elements, 6th edition, II. 707. 



