S. Taker — Growth of Crystals. 



545 



in fine capillary tubes remained in a liquid state at very low 

 temperatures.* This suggested the following experiment : A 

 half-inch glass tube and a fine capillary tube were filled with a 

 concentrated solution of copper sulphate and sealed. The 



Fig. 3. 



Fig. 3. Porous battery cell in a saturated solution of copper sulphate. 

 The solution is drawn up through the capillary poi'es and on evaporating 

 from the upper siirfaces deposits crystals which rupture the cell and gradu- 

 ally form veinlets. 



temperature was then lowered until crystals began to separate 

 out in the large tube, but crystallization did not take place in 

 the capillary tube even when it was kept at a much lower 

 temperature for several days. The discovery of this fact led 

 to a series of experiments with porous materials, two of which 

 are described below. 



*This fact seems first to have been observed and recorded by Sorby, Phil. 

 Mag. (4), vol. xviii, p. 105, 1859. 



