Royal Society. 541 



HI HI 



H J>N + XBr=H VN.HBr. 

 Hj Xj 



HI H] 



" ^>N + YBr=X SN.HBr. 

 YJ 



H : 

 Xj 



HI XT 



X >N+ZBr= Y VN. 

 Yj Zj 



HBr. 



For the illustration of these general formulae, one of the numerous 

 sets of experiments which the author has communicated in his paper 

 may be quoted in which X= Y=Z. Ammonia, when exposed to the 

 action of bromide of ethyl (hydrobromic ether), is converted into 

 hydrobromate of ethylamine, i.e. ammonia in which 1 equivalent of 

 hydrogen is replaced by ethyl, a compound which was first observed 

 by M. Wurtz under perfectly different circumstance?. Ethylamine, 

 treated again with bromide of ethyl, yields a new alkaloid diethyla- 

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

 by ethyl, 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. 



Jan. 24. — Observations on the Freezing of the Albumen of Eggs. 

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

 Royal College of Surgeons. Communicated by Thomas Bell, Esq., 

 Sec. R.S. &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 very 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 ' vital power' of the egg in the first case, and 

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

 author's experiments confirm those of Mi'. 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 bj'' 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 M'as lost by the several 

 eggs, exposed to temperatures varying from zero to 10°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 without freezing, 

 although its proper freezing-point is at or just below 32°. Other 

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

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



