386 LETTERS ON NATURAL MAGIC. 



inhalation of paradise or intoxicating gas, as it has been 

 called. This gas is known to chemists by the name of the 

 nitrous oxide, or the gaseous oxide of azote, or the protoxide 

 of nitrogen. It differs from atmospheric air only in the 

 proportion of its ingredients, atmospheric air being com- 

 posed of twenty-seven parts of oxygen and seventy-three of 

 nitrogen, while the nitrous oxide consists of thirty-seven 

 parts of oxygen and sixty-seven of nitrogen. The most 

 convenient way of procuring the gas is to expose nitrate of 

 ammonia in a tubulated glass retort to the heat of an 

 argand's lamp between 400 and 500 of Fahrenheit. The 

 salt first melts ; bubbles of gas begin to rise from the 

 mass, and in a short time a brisk effervescence takes place, 

 which continues till all the salt has disappeared. The 

 products of this operation are the nitrous oxide and 

 water, the watery vapour being condensed in the neck of 

 the retort while the gas is received over water. The gas 

 thus obtained is generally white, and hence, when it is 

 to be used for the purposes of respiration, it should remain 

 at least an hour over water, which will absorb the small 

 quantity of acid and of nitrate of ammonia which adhere 

 to it. A pound of the nitrate of ammonia will in this way 

 yield five cubic feet of gas fit for the purpose of inhala- 

 tion. 



It was discovered by Sir Humphry Davy, that this gas 

 could be safely taken into the lungs, and that it was 

 capable of supporting respiration for a few minutes. In 

 making this experiment he was surprised to find that it 

 produced a singular species of intoxication, which he thus 

 describes : " I breathed," says he, " three quarts of oxide 

 from and into a silk bag for more than half a minute 

 without previously closing my nose or exhausting my 

 lungs. The first inspiration caused a slight degree of 

 giddiness. This was succeeded by an uncommon sense of 

 fulness in the head, accompanied with loss of distinct 



