SECTION 20. STUDIES PREPARATORY TO ALL INVESTIGATIONS. 233 

 III. THIRD ILLUSTRATION. 



102. In the process of inhaling laughing gas, I accidentally 

 injure my knee, and observe that the injury is not accompanied 

 by pain, as would be normally the case. Assuring myself by 

 varied experiments that laughing gas produces this anaesthetic 

 effect, I conclude provisionally that all bodily pain may be thus 

 overcome, and that laughing gas, or some perhaps even more 

 effective gas, or other substance, should be administered in all 

 dental and surgical operations and wherever there is pain diffi- 

 cult to endure. I proceed then with the investigation on estab- 

 lished methodological lines, following strictly Conclusion 3. 



/. Material Aspects. 



1. We inquire what appeal nitrous oxide makes to the sen- 

 ses to sight, touch, effort, pain, hearing, taste, smell, and heat. 

 Also what feelings its presence or inhalation engenders, or what 

 is its effect on the will and the intelligence. Finally, whether 

 it is only indirectly apprehensible. 



2. We inquire into the nature of the constituents of the gas. 



3. We inquire into its form. 



4. We inquire into the precise special facts and factors in 

 the environment on which the gas more or less depends for 

 its existence. 



5. We make a study of its precise effects. 



6. We trace the cause of its existence and properties. 



7. We then consider the relation of laughing gas to other 

 anaesthetics. 



8. We ascertain the points wherein it resembles other an- 

 aesthetics. 



9. We classify the facts pertaining to laughing gas, and then 

 place the gas under a more comprehensive classification. 



10. We determine the comparative position of laughing gas 

 among anaesthetics. 



11. We inquire into the major and minor differentiae of 

 laughing gas. 



12. And we consider the secondary aspects or details. 

 We take into account then the practical side: 



13. We inquire into the hygienic, economic, moral, aesthetic, 

 scientific, philosophical, and other, value of nitrous oxide. 



14. We consider the problems involved in its utilisation, 

 application, and production. 



15. And we consider men's subjective attitude towards it their 

 like or dislike thereof. 



that "the ultimate Laws of Nature cannot possibly be less numerous than 

 the distinguishable sensations or other feelings of our nature". (Bk. 3, 

 ch. 14, 2.) In reasoning thus he begs the question, for the various sensations 

 are most probably complexes, and therefore neither ultimate nor irreducible. 



