16 SALINE SOLUTIONS, ALCOHOL, ETC., MIX 



pores, in the form of crystals. If the tube be filled 

 originally with dilute saline solution, the crust of 

 salt is not formed on the outer surface of the 

 bladder until the solution in the tube has reached, 

 by evaporation, the maximum of saturation. Be- 

 fore this takes place, we can perceive in the tube, 

 if we set the liquid in motion, two strata, a heavier 

 and a lighter, the latter swimming on the former. 

 When these strata can no longer be observed, the 

 liquid is in every part saturated with salt, and now, 

 by further evaporation, crystals are deposited on the 

 outer surface of the bladder. This last circumstance 

 proves that the amount of salt in the liquid is uni- 

 formly distributed from below upwards, from the 

 specifically heavier to the specifically lighter part. 

 Saline so- If we immerse the tube closed with bladder, and 

 very rapidly filled with saline solution, in pure water, the latter 

 bladder. acquires the property of precipitating nitrate of 

 silver, even when the contact has lasted only the 

 fraction of a second. The brine filling the open 

 pores of the membrane mixes with the pure water, 

 and the latter acquires a certain quantity of salt. 



In like manner, the pure water acquires a saline 

 impregnation, when it is placed in the tube instead 

 of brine, and the outer surface of the bladder is 

 placed in contact with solution of salt. 



When the tube, closed with bladder, and filled 

 with brine, is left for a long time with the closed 

 end immersed in pure water, the amount of salt in 

 the latter increases, while that of the brine dimi- 



