21 S TEAK-BOOK OF FACTS. 



egg contains little or no air ; and if atmospheric air be excluded, its 

 absorption prevented, as by lubricating the shell with oil or any- 

 oleaginous matter, the albumen retains for a considerable time the 

 qualities of the newly-laid egg. This is a fact well known to dealers 

 in eggs. 



"The exact time required for the change to take place, owing to 

 the absorption of air, I cannot exactly say ; it varies, I believe, in 

 some measure, according to the season —a shorter time in winter 

 being required than in summer; the egg, in the former season, 

 owing to lower atmospheric temperature, contracting more in bulk, as 

 regards its substance, than in the latter. A very few days, as from 

 five to six at furthest, seem to be sufficient. In April I have ob- 

 served the milkiness on the fourth, but not later. On the contrary, 

 if air be excluded, I do not know how long the quality of the newly- 

 laid egg may not be preserved. I have found an egg laid in the 

 month of April, and then smeared with butter, hardly appreciably 

 changed at the end of six months. 



"Nor can I speak with any exactness respecting the amount of 

 air, of oxygen absorbed, or of other alterations that may be effected 

 in the composition of the egg by its action. All that I have yet 

 ascertained is, that with the absorption of oxygen in the instance of 

 the stale egg, carbonic acid is formed, and ammonia, and the colour 

 of the albumen is darkened, it becoming of a light brownish yellow, 

 and at the same time acquiring a smell somewhat unpleasant, and a 

 taste, as^is well known, not agreeable. The putrefactive process, I 

 believe, does not take place, however long the egg may be kept, 

 unless there be some admixture of the yolk and white." 



Dr. Davy has extended his trials to the eggs of the duck, the 

 turkey, and the guinea-fowl, with similar results. — Abridged from 

 the Edinburgh Philosophical Journal, No. 22. 



FLIGHT OF BIRDS. 



Dr. John Davy, in a paper on the Specific Gravity of Birds, 

 communicated to the Edinburgh Philosophical Journal, No. 22, 

 says : "In conclusion, it may be remarked, that, judging from the 

 foregoing results, the specific gravity of the body of birds is con- 

 cerned but in a very subordinate manner with their aptitude for 

 aerial locomotion. That aptitude seems to depend on other cir- 

 cumstances, such as the great lightness of their feathers, owing to 

 the air which they contain ; the little tendency of water to adhere 

 to them, even when exposed to rain ; their form and arrangement, 

 so admirably adapted for the purpose of impulse ; the high tem- 

 perature of the body expanding the contained air ; and the Immensely 

 powerful muscles, the pectoral, belonging to the wings. Is not the 

 power of (light of each species in a great measure proportional to 

 these conditions '(" 



stomach of the fi 

 Dr. John Davy closes a paper " On the Stomach of the Fish," 



