1872.] Mr. A. Liversidge on Supersaturated Saline Solutions. 503 



from the part of the solution through which it would pass on being 

 drawn up. 



The bucket, now full of the crystallized normal sodic sulphate (Na 2 S0 4 , 

 10H 2 O), was raised, and lowered into the second beaker of still fluid solu- 

 tion ; immediately that the point of one of the crystals hanging from the 

 under surface of the bucket touched the solution, crystallization was set up 

 instantaneously throughout the mass. 



This experiment was performed many times, and with every possible 

 care to prevent the entrance of nuclei other than those purposely borne by 

 the wire. 



A modification of the above plan was tried and with similar results. 



Exp. A tubulated glass bell was fitted with a cork bearing two glass 

 tubes, open below and closed above with cotton-wool ; they were bent so 

 as to permit both of them being placed in one and the same beaker, or 

 into either separately. 



In the first place, the ends of the tubes inside the bell were freed from 

 nuclei by passing them through a flame ; two beakers of cold supersatu- 

 rated solution were then placed in position under the bell-jar, and their 

 covers removed. After waiting five minutes or so for any dust to settle, 

 both tubes were next lowered into one of the beakers, on opposite sides, 

 so as to be as far apart as possible. A dirty wire was now passed down 

 one of the tubes, when, of course, crystallization immediately took place, 

 and was propagated across the beaker. The second tube, with its adhe- 

 ring crystals, was then raised and lowered into the second beaker, when, 

 the moment the extreme point of the longest crystal touched the surface 

 of the solution, crystallization immediately started from that point, and 

 the whole contents became solid. 



A third variation was then made in this experiment. One of the two 

 beakers was replaced by a U-tube of thin, hard glass, one of the before- 

 mentioned tubes being inserted into either limb. Crystallization, when set 

 up in one limb, travelled round the bend and up into the other, from which 

 crystals were transferred, as before, to a beaker or flask of solution also 

 under the bell-jar. 



The three modifications of this form of experiment were tried time after 

 time, and always with the same unvarying result. Solutions which were 

 supersaturated although not perfectly, and therefore less sensitive, were 

 operated upon in this way ; but, even with such less favourable circum- 

 stances, the normal crystals always started crystallization in the solution 

 to which they were added. 



To ascertain, if possible, whether nuclei, other than crystals of the normal 

 salt, were carried by the tube or its adhering crystals, a capsule of sul- 

 phuric acid was placed under the bell. The crust of crystals was by this 

 means dried, and became effloresced to a greater or less extent. Now, on 

 lowering them into a supersaturated solution of alum or of magnesic sul- 



