574 INDUCTION. 



equator will originate a voltaic circuit, and waterfalls 

 will naturally become electric. 



For a second example ; it has recently been found, 

 chiefly by the researches of Professor Graham, that 

 gases have a strong tendency to permeate animal 

 membranes, and diffuse themselves through the 

 spaces which such membranes inclose, notwithstand- 

 ing the presence of other gases in those spaces. 

 Proceeding from this general law, and reviewing a 

 variety of cases in which gases lie contiguous to 

 membranes, we are enabled to demonstrate or to ex- 

 plain the following more special laws : 1st. The human 

 or animal body, when surrounded with any gas not 

 already contained within the body, absorbs it rapidly; 

 such, for instance, as the gases of putrefying matters : 

 which helps to explain malaria. 2nd. The carbonic 

 acid gas of effervescing drinks, evolved in the sto- 

 mach, permeates its membranes, and rapidly spreads 

 through the system, where, as suggested in a former 

 note, it probably combines with the iron contained in 

 the blood. 3rd. Alcohol taken into the stomach (the 

 temperature of the stomach is above the boiling-point 

 of pure alcohol,) passes into vapour and spreads 

 through the system with great rapidity ; (which com- 

 bined with the high combustibility of alcohol, or in 

 other words its ready combination with oxygen, may 

 perhaps help to explain the bodily warmth immediately 

 consequent on drinking spirituous liquors.) 4th. In any 

 state of the body in which peculiar gases are formed 

 within it, these will rapidly exhale through all parts 

 of the body; and hence the rapidity with which, in 

 certain states of disease, the surrounding atmosphere 

 becomes tainted. 5th. The putrefaction of the inte- 

 rior parts of a carcase will proceed as rapidly as that 

 of the exterior, from the ready passage outwards of 



