LAUGHING GAS. 31 



derived from this gas dissolved in water, carried 

 up by the roots, and metamorphosed in the 

 leaves ! 



This variety of result may be illustrated in 

 another manner. The acrid, dangerous, and 

 highly corrosive liquid well known to every 

 person as aquafortis, or impure nitric acid, in 

 its pure condition one of the most powerful 

 re-agents of the laboratory, is composed of ni- 

 trogen and oxygen. These are also the consti- 

 tuents of the summer breeze ! Whence then 

 this notable change? The answer is, 1st, the 

 relative proportions or quantities of the two 

 elements are not the same in the one the pro- 

 portion of oxygen to that of nitrogen is much 

 greater than in the other ; and 2nd, in the case 

 of the nitric acid the elements are in chemical 

 union, in the air they are only in a state of 

 mixture. Thus an apparently trivial alteration 

 in chemical conditions and proportional num- 

 bers effects a change of the most unexpected 

 and startling order ! Another alteration again 

 in our atmosphere would produce "laughing 

 gas," a substance whose stimulating properties 

 have supplied its title. Not to proceed further, 

 here are three- products, of the most entirely 

 opposite and unlike character, namely, nitric 

 acid, atmospheric air, and laughing gas, com- 

 posed of precisely the same elements. Why then 



