906 



mine, i.e. ammonia in which 2 equivalents of hydrogen are replaced 

 by ethy], and which, under the influence of a further quantity of 

 bromide of ethyl, lastly is transformed into triethylamine, or ammonia 

 in which the whole of the hydrogen is replaced by ethyl. This is 

 a most powerful alkali, whose properties resemble those of caustic 

 potassa. 



January 2-i, 185U. 

 RICHARD OWEN, Esq., Vice-President, in the Chair. 

 The following communications were read : 



1. Observations on the Freezing of the Albumen of Eggs." By 

 James Paget, Esq., Professor of Anatomy and Surgery to the Royal 

 CoUeo-e of Surgeons. Communicated by Thomas Bell, Esq., Sec. 

 R.S. d-c. 



The object of this paper is to illustrate a peculiar property of the 

 albumen of the eggs of birds, a property which seems to have its pur- 

 pose in preserving them from the injurious effects of yery low tem- 

 peratures. 



Mr. Hunter observed that a fresh egg will resist freezing longer 

 than one which has been previously frozen and thawed; and he re- 

 ferred this fact to the ' yital power' of the egg in the first case, and 

 the destruction of that power by freezing in the second. The 

 author's experiQieuts confirm those of Mr. Hunter, and prove, also, 

 that when fresh eggs are exposed to very low temperatures, and also 

 in the case of eggs which are decayed, or putrid, or the contents of 

 which have been much altered by mechanical force or by electricity, 

 a shorter time is sufficient for the freezing of such eggs, than is 

 necessary for the freezing of those which.are uninjured. 



An examination of the rates at which heat was lost by the several 

 eggs, exposed to temperatures varying from zero to lO'Fahr., showed 

 that fresh eggs, though they resist freezing longer than any others, 

 yet lose heat more quickly ; and that their resistance to freezing is 

 due to the peculiar property of their albumen, the temperature of 

 which may be reduced to 16" Fahr,. or much lower vv-ithout freezing, 

 although its proper freezing-point is at or just below S'2". Other 

 than fresh eggs lose heat comparatively slowly, but freeze as soon 

 as their temperature is reduced to 32^; fresh eggs lose heat more 

 quickly, but may be reduced to 16" or lower ; then, at the instant of 

 beginning to freeze, their temperature rises to 32^ 



That this peculiarity of fresh eggs is not due to vital properties, 

 is proved by experiments which show that certain injuries, such as 

 mechanical violence, addition of water, and others, which spoil their 

 povrers of resisting freezing, do not prevent eggs from being deve- 

 loped in incubation. By the same and other experiments, Avhich are 

 related, it is made probable that the peculiarity depends on the me- 

 chanical properties of the albumen ; for, whatever raakes the albumen 

 more liquid than it is naturally in the fresh egg, destroys the power 

 of resisting freezing. 



