Sir Humphry Davy 111 



I have seen some of the adventurous philosophers who 

 sought in vain for satisfaction in the bag of ' Gaseous 

 Oxyd,' and found nothing but a sick stomach and a 

 giddy head." 



As a result of further experiments with nitrous oxide, 

 Davy mentions its power of destroying physical pain and 

 suggests its application in surgical operations; but no 

 notice of this suggestion was taken for half a century. 

 Davy's researches on gases were preceded by the unhappy 

 publication already referred to " On Heat, Light, and the 

 Combinations of Light, with a new Theory of Respiration," 

 in which he tries to demolish Lavoisier's theory that oxygen 

 was a compound of an elementary substance and " heat." 

 The paper is in great part of a speculative nature, and full 

 of hasty and ill-considered opinions. He was, no doubt, 

 right in his contention that heat is not a substance, but he 

 spoils his case by adhering to the belief in the compound 

 nature of oxygen, replacing only Lavoisier's " heat " by 

 the equally imaginary substance " light." He tries to prove 

 by experiments which are not to the point that light is not 

 due to the vibrationary motion of an elastic medium, and 

 even states that oxygen cannot be produced from oxide of 

 lead by heating it in the dark. A statement of this kind 

 renders it doubtful whether he was sufficiently careful in 

 excluding all possible sources of error in another experiment, 

 described in the same paper, in which two pieces of ice 

 were melted in an exhausted receiver by rubbing them 

 together. 



The errors of a self-trained, impulsive young man would 

 hardly be worth recording were it not for the chastening 

 effect which the severe criticisms they evoked had on his 

 subsequent work. Davy never forgot his lesson; he 

 remained impulsive, but became much more careful in his 

 experiments, and avoided speculative theories like a child 

 avoids fire when it has burnt its fingers. Within a year he 

 published a letter in Nicholson's Journal, in which he says : 

 " I beg to be considered as a sceptic with regard to my 

 particular theory of the combinations of light, and theories 

 of light generally." Before we leave Davy's activities at 

 Bristol, we may quote a passage from one of his letters 



