70 



seems to authorise the conclusion, that, while the 

 oxygen gas had, in this case, completely disappear- 

 ed, the nitrogenous portion of the air continued un- 

 diminished, and probably unaltered. 



55. M. Vauquelin proceeded next to investigate 

 the changes produced on the air by the respiration 

 of the wrmes class of animals. He confined a red 

 slug in twelve cubic inches of atmospheric air, and 

 it lived forty-eight hours. He thinks, that in this 

 animal the breathing pores are situated chiefly be- 

 hind the head. The air was not sensibly diminish- 

 ed in volume, but it extinguished candles, and copi- 

 ously precipitated lime from water. Phosphorus 

 was melted in this air, but did not suffer any com* 

 bustion or change of colour. A snail (helix fioma- 

 tia) was next put into twelve cubic inches of atmo- 

 spheric air, and lived four days. The oxygen gas 

 entirely disappeared ; for the residual nitrogen gas 

 contained not an atom of vital air, and, consequent- 

 ly, phosphorus did not burn in it at all : it contain* 

 ed, however, carbonic acid. Slugs and snails, there- 

 fore, require fresh air while in an active state, the 

 oxygen gas of which, by the function of their respi- 

 ratory organs, is made completely to disappear, and 

 a quantity of carbonic acid is produced, while the 

 nitrogenous portion of the air remains unaltered : 

 and when these changes are effected, living action 

 speedily comes to an end. So exactly do these ani- 

 mals separate the oxygenous from the nitrogenous 

 portion of the atmosphere, that M. Vauquelin sug- 

 gests the employment of them for eudiometrical pur* 

 poses *. 



* Ann* de Chimie, loc. cit. 



