1878.] 



The Function of the sides of the Vessel, fyc. 



189 



VIII. Fresh-water Ice. Flame 6 inches from nearest Thermometer. 

 Temperature of outer air = — 37°. January 3, 1876. 

 Heat applied continuously for two hours. 



Time. 



Ther. 1. 



Ther. 2. 



Ther. 3. 



Ther. 4. 



Tempera- 

 ture of ice 

 house. 



Ther. 

 Y.Y. 



hours min. 

 9 46 

 10 1 

 in l r 



iw ID 



10 31 



10 46 



11 1 

 11 16 

 11 31 

 11 46 







-23 

 -22-25 

 — 21 

 -20-1 

 -19-75 

 -19 -25 

 -19-5 

 -19 -25 

 -19 



o 



-24 



-24 



— 23 -5 



-23-25 



-23 



-23 



-23 



-23 1 



-23 



-21° 



-20-75 



— 20 -5 



-20-5 



-20 -25 



-20-25 



-20-5 



-20-5 



-20-25 







-20 



-20 



— 19 "9 



-20 



-20 



-20 



-20 



-20-25 



-20 



o 



-21 



-20-75 



— 20 '5 



-20-75 



-20-5 



-20-5 



-21 



-20-9 



-20-75 



o 



-23 



-22 



— 22 



-22 



-22-75 



-23 



-23 



-22-5 



-22 25 



Range in 1 hr. 

 Range in 2 hr. 



3-25 

 4 



1-0 

 1 



0-75 

 0-75 





 



0-5 

 0*25 



25 

 0-75 



Til. " On the Function of the Sides of the Vessel in maintaining 

 the State of Supersaturation." By CHARLES TOMLINSON, 

 F.R.S. Received February 21, 1878. 



Before any consistent theory can be framed of all the phenomena of 

 supersaturated saline solutions, it is necessary to determine whether 

 the sides of the vessel bear any, and what part, in maintaining the 

 state of supersaturation. 



It is remarkable that among the multitude of memoirs and papers 

 that have been published on the subject of supersaturation generally, 

 and of special phenomena in particular, my reading should not have 

 made me acquainted with any special experimental researches con- 

 ducted with the view of determining the point in question. 



In 1819, Gay-Lussac* seeing how easily a supersaturated solution 

 of sodic carbonate can be made to solidify, by merely shaking the 

 vessel, expressed his opinion that the state of supersaturation depends, 

 not on a chemical, but a purely mechanical force. "We cannot," he 

 says, " fix the point at which supersaturation ends, since it is entirely 

 accidental in each experiment, depending, as it does, on the nature of 

 the vessel, its polish, its conducting power, and the agitation of the 

 air." 



In 1851 Lamyt arrived at the conclusion that the form, thickness, 

 and nature of the vessel, and the quantity of solution contained 

 therein, have no influence on the state of supersaturation. 



* Ann. de Ch. et Phy., 2e Serie, xi, 303. f Comptes Rendus. 



o2 



