42 Mr. C. Tomlinson on Supersaturated Saline Solutions. [Nov. 23, 



The same flask was reboiled and left to cool during an hour. It was 

 put out at 5.15; temp. 55°, with clouds; at 6, temp. 4/J°; at 6.35, 

 temp. 45°. At 7.15 the seven-watered salt was forming and heat-currents 

 ascending ; cloudy. At 9, the seven-atom salt was much increased in quan- 

 tity ; temp. 45°. At 9.45, the solution solid, the nuclear action directly 

 under the mouth of the flask. 



March 19. Added a small quantity of water to supply waste from evapo- 

 ration and reboiled the same flask. When cold, put the flask out at 5 p.m. 

 At 6.30 brought it back into room, and it crystallized within two or three 

 minutes. 



Reboiled this flask and put it uncovered in the garden to cool at 6.35. 

 At 8.45 foggy, and temp. 43°. Shook the solution ; it was very viscous, 

 but did not crystallize. At 9.30 abundant deposit of moisture : at 10.30 

 thick mist, temp. 41|°; no crystallization. 



March 20. At 7 a.m. found a considerable deposit of the seven-watered 

 salt, much of it finely crystallized ; flask and stool very wet; temp. 40°. 

 Took the flask indoors, and after a few minutes the solution crystallized 

 and the seven-atom salt became opaque. There was a speck of soot on 

 the solution, but it lay so loosely that it had evidently not disturbed the 

 surface-tension of the solution. 



Three flasks were put out in the garden and uncovered. One crystallized 

 from the action of a speck ; a second during the day deposited some seven- 

 watered salt and then crystallized by evaporation, producing some very 

 fine crystals of the ten-watered salt with dihedral summits. These crystals, 

 although so fine, were produced rapidly (as under the action of films), as 

 was evident from phenomena which may often be seen in the sudden crys- 

 tallization of supersaturated solutions, namely, the heat liberated in the 

 passage of the liquid to the solid state volatilizes a portion of the water of 

 the solution, and the vapour rising upwards towards the neck condenses 

 on the inner surface of the flask ; but the ring of glass just above the soli- 

 dified solution is rendered too warm to condense the vapour, so that the 

 flask presents the curious appearance of salt at the bottom in a chalky white 

 deposit covered by a layer of crystals or by an opalescent layer; then 

 comes a zone of clear glass surmounted by a wide deposit of condensed 

 vapour. The heat thus given out during the solidification of supersaturated 

 saline solutions may vary from 10° or 20° to 100° F. 



The third flask put out under this date crystallized some hours later by 

 evaporation. 



April 25. Flask out all night. This morning found it covered with 

 dew, some of which trickled down into the solution without acting as a 

 nucleus. 



April 27. Two flasks put out, and after a few hours rain came on and 



was kind enough to suggest that the large crystals might be due to evaporation. Such 

 was certainly the case ir. some of these garden experiments. 



