PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 465 



Sir Humphrey Davy, about the year 1800, studied minutely the 

 qualities of uitrous oxide, and as it contained only the main constitu- 

 ents of common air, he was induced to try its effect upon himself by 

 breathing it, and was the first to discover that its inhalation pro- 

 duces an exhilcrating effect upon the nervous system, and hence 

 it was afterwards known by the popular name of laughing gas. 



Dr. Henry said, as early as 1823, "that although this gas proves 

 fatal to animals wholly confined in it, j^et it has no injurious effect 

 when admitted into the human lungs, because it is there mixed 

 and diluted with the air present in that organ. To administer the 

 gas it may be introduced into an oiled silk bag or clean bladder, 

 furnished with a stop-cock, and may be breathed repeatedly from 

 the bag: and back again as long; as it will last. The sensations that 

 are produced vary greatly in persons of different constitutions; 

 but in general they are highly pleasurable and resemble those 

 attendant on the early period of intoxication. Great exhileration, 

 an irresistible propensity to laughter, a rapid flow of ideas and an 

 unusual fitness for muscular exertion are the ordinary feeling it 

 produces. These pleasant sensations, it must be added, arc not 

 succeeded, like those accompanying the grosser elevation from 

 fermented liquors, by any subsequent depression of nervous 

 energy." 



Such was the estimate of the effect of this gas more than forty 

 years ago. It has been said some disastrous consequences have 

 followed the breathing of this gas, but in these cases the evil 

 doubtless arose from using an impure gas. The gas is most 

 readily made from the nitrate of ammonia which is resolved into 

 nitrous oxide and water by appl^'ing from four to 500° F. of heat, 

 but if a higher heat is employed, it is said, nitric oxide is also 

 formed. With proper care, however, a very pure gas may be 

 made by first forming the nitrate of ammonia from pure carbonate 

 of ammonia, subject to the action of pure nitric acid — and submit- 

 ting the resulting nitrate to a very regular temperature not exceed- 

 ing 500^ F. 



The effect of inhaling nitrous oxide, as already described, is 

 rapidly changed if the process is continued, and the laughing gas 

 then acts as a sedative. The overcharged nerves are suddenl}'^ 

 relaxed and the inhaler sinks into a dreamy and unconscious state. 

 In this condition he is wholly insensible to pain, but insensibility 

 to pain does not wholly arise after unconsciousness. In some cases 



[Am. Inst.] DD 



