314 THE KOYAL INSTITUTION. [CHAP. VI. 



expecting that some of our experiments would produce 

 results worthy of communication. 



I am now as much convinced of the non-existence of 

 caloric as I am of the existence of light. 



Our laboratory in the Pneumatic Institution is nearly 

 finished. 



I hope the gaseous oxide of azote will prove to be a 

 specific stimulus for the absorbents. 



I know of little general scientific news. Berthollet makes 

 sulphuretted hydrogen out to be an acid. 



I remain, with affection and respect, yours, 



HUMPHRY DAVY. 



Again on April 10, 1799, to Mr. Gilbert, writing of 

 light and heat, he said : 



The supposition of active powers common to all matter 

 from the different modifications of which all the phenomena 

 of its changes result, appears to me more reasonable than 

 the assumption of certain imaginary fluids, alone endowed 

 with active powers, and bearing the same relation to com- 

 mon matter as the vulgar philosophy supposes spirit to 

 bear to matter. 



It is only by forming theories, and then comparing them 

 with facts, that we can hope to discover the true system of 

 nature. 



I made a discovery yesterday which proves how necessary 

 it is to repeat experiments. The gaseous oxide of azote is 

 perfectly respirable when pure. It is never deleterious 

 but when it contains nitrous gas. I have found a mode of 

 obtaining it pure, and I breathed it to-day in the presence of 

 Dr. Beddoes and some others sixteen quarts of it for near 

 seven minutes. It appears to support life longer than even 

 oxygen gas, and absolutely intoxicated me. Pure oxygen 

 gas produced no alteration in my pulse nor any other 

 material effect, whereas this gas raised my pulse upwards 



