28 Mr. C. Tomlinson on the Action of Solid Nuclei. [May 8, 



placed at an angle of about 45°, so that if any spitting occurred it 

 would be against the belly of the flask and not into the neck. The 

 necks were covered with small beakers, taken out of water, and the 

 flasks were thus conveyed to the outer air and left to cool, the tem- 

 perature being 40°. When cold, some absolute alcohol in a small 

 clean beaker was taken up by means of a clean dropping tube, and a 

 single drop or a number of drops was delivered to the surface of each 

 solution without contact with the interior of the neck, the covering 

 beaker, in each case, being lifted a little on one side so as not com- 

 pletely to uncover the mouth of the flask or admit the rain. The 

 sodic sulphate solution in several cases became solid directly the 

 alcohol reached it ; in other cases after some minutes ; in two flasks 

 the alcohol acted by determining a copious deposit of the modified 

 salt,* but the solution in one of them became solid on gently shaking it, 

 and in the other equally so on adding a few more drops of alcohol. In 

 the case of the alum solution the results were similar. As soon as the 

 alcohol reached the surface there was a sort of trembling motion, as 

 if the surface tension had been disturbed, and also a kind of viscous 

 disturbance in the solution (phenomena equally applicable to the sodic 

 sulphate solutions), when suddenly a single octohedral crystal would 

 start into existence just below the surface ; or, if a number of drops 

 of alcohol had been added, a multitude of minute octohedra would all 

 at once appear at the surface plane between the two liquids ; or, 

 thirdly, the action would begin from the bottom, and a large crys- 

 talline mass be formed, while heat currents rapidly ascended ; or, 

 fourthly, on gently shaking the flask, an immense assemblage of 

 chalky- white points filled the solution and made it opaque. In no 

 case did the alcohol fail to exert a nuclear action. 



By way of contrast with the above results, the experiments were 

 repeated on another wet day, when the wind was veering between 

 south-east and south-west. The alcohol was now inactive so far as 

 the solidification of the solutions was concerned, but active in throw- 

 ing down a large quantity of the modified salt. The day after this 

 the wind blew steadily from the north, and alcohol, ether, naphtha, 

 and wood spirit were all active on solutions of sodic sulphate and 

 potash alum, the former becoming solid immediately, and the latter 

 within two or three minutes. 



Now, if it be still asserted that whenever these solutions become 



* Lowel, in his first memoir, says that if alcohol be introduced into a supersatu- 

 rated solution of sodic sulphate, it immediately produces the ten-atom or normal 

 salt with solidification of the solution ; but if a large quantity of alcohol, at 36° to 

 40° C, be introduced, crystallization does not take place on cooling. If now the 

 flask be left to repose, the alcohol takes water from the solution, concentrates it, and 

 in two or three days produces the seven-atom or modified salt in fine crystals on 

 the surface of the liquid in contact with the alcohol. 



