194 



shell, forming a fine and transparent net-work. A 

 hen's egg was placed in three cubic inches of atmo- 

 spheric air, inverted over mercury: on examining 

 the air at the end of the fourth day, it was some- 

 what diminished in bulk, its nitrogenous portion re- 

 mained unaltered, a large quantity of its oxygen had 

 disappeared, and a portion of carbonic acid was pro- 

 duced. This diminution of the oxygen could not 

 be owing to any supposed attraction of it by the 

 substance of the egg ; for the shell, when deprived of 

 its contents, was found to produce a similar effect on 

 the air *. As the carbonic acid in this, as well as in 

 the former instances, was formed when the air and 

 the egg were in contact, and neither of them sepa- 

 rately could produce it, it is evident that the air must 

 have furnished the gas, while the egg supplied the 

 carbon. It is known that an exhalation is constant- 

 ly going on from the egg, by which it is daily be- 

 coming lighter ; and the more rapidly this exhalation 

 proceeds, the sooner does the egg decay. The egg 

 of a sparrow, weighing 29 grains, was exposed on a 

 table in a room varying from 60 to 66 Fahrenheit. 

 By the third day, it had lost one grain : by the fifth 

 day, two grains : by the tenth, three grains : by the 

 seventeenth, four and a half grains : and by the twen- 

 ty-sixth day, six grains: when broken, its contents 

 were very putrid. A fresh hen's egg, weighing 13 

 drachms, and exposed in the same room from June 

 15. to July the 30th, lost in weight 2 drachms 2O 

 grains : while another egg, equally exposed, but 



* . Memoirs on Respiration, p. 237. ct seq. 



