208 



Mr. C. Tomlinson on 



[Mar. 13, 



the five pairs of legs, and the abdominal feet; they show that Tkaumops has 

 to undergo no metamorphosis, and that the young ones leave the eggs 

 with all their appendages well developed. 



Mode of life. — It could not be made out whether T. pellmida inhabits 

 the deep sea, or whether it is, like Phronima, a pelagic animal, having 

 been caught by the trawl only as the latter came up from the depths. 



H.M.S. ' Challenger/ Teneriffe, 

 February 13, 1873. 



March 13, 1873. 



WILLIAM SPOTTISWOODE, M.A., Treasurer and Vice- 

 President, in the Chair. 



The following communications were read : — 



I. "Note on Supersaturated Saline Solutions." By Charles 

 Tomlinson, F.R.S. Received February 10, 1873. 



In the year 1866, M. Grernez and M. Yiollette published each a memoir 

 on supersaturated saline solutions *, in which the same conclusions are 

 arrived at, namely : — (1) that the only nucleus capable of suddenly crys- 

 tallizing any one of such solutions is a salt of the same kind as that dis- 

 solved ; and (2) that all bodies, solid, liquid, or aeriform, which apparently 

 act as nuclei, are really contaminated with a hydrate of the salt that forms 

 the supersaturated solution. 



I cannot refrain from expressing my admiration at the unwearied skill 

 and patience with which these two memoirs were prepared. The experi- 

 ments were repeated by hundreds, and under a large variety of circum- 

 stances, so that it seems scarcely possible to entertain any doubt as to 

 the validity of the conclusions arrived at. I had not seen these memoirs 

 until long after the publication of my second paper on this subject f, or 

 I should have hesitated in offering it to the Royal Society without spe- 

 cial reference to them. What I did see was a very brief abstract of M. 

 Gernez's memoir in the ' Comptes Rendus,' and to this I refer in my first 

 paper J, quoting the experiments and the decisive objections of M. Jeanne] 

 in opposition to M. Qernez's conclusions. 



The experiments of Mr. Liversidge § are identical in principle with 



* Annales Scientifiques de l'Ecole Normale Superieure, tome 3 e , Annee 1866, 

 pp. 167 and 205. I am indebted for this reference to the courtesy of M. l'Abbe 

 Moigno. 



t Phil. Trans. 1871, p. 51. 



% Phil. Trans. 1868, p. 660. The reference to M. Jeannel is in the abstract of this 

 paper contained in the ' Proceedings of the Koyal Society,' May 28, 1868, p. 405. 

 § Proceedings of the Koyal Society, vol. xx. p. 497. 



