36 LAWS OF THE MIXTURE 



iron. The stratum of iron lying next under this 

 surface, which has the same attraction for carbon, 

 acquires carbon from the superficial stratum imme- 

 diately in contact with it, and in its turn gives carbon 

 to the stratum below itself. This process, if con- 

 tinued long enough, has no limit till all the strata of 

 particles have acquired an equal proportion of car- 

 bon, that is, till they are all saturated with it. A 

 piece of red-hot malleable iron, if kept a few mo- 

 ments in contact with pig iron (a carburet of iron) 

 is found to be already converted into steel at the 

 points of contact. The mixture of liquids depends 

 on the same principle ; and we may suppose that 

 their distribution is mutual, because their particles 

 may move in all directions, and that consequently 

 saline particles move towards aqueous particles, as 

 well as aqueous towards saline particles, in virtue 

 of their mutual attraction. 



From a solution of sulphate of copper in ammo- 

 nia, placed in a tall glass cylinder, there is gradually 

 separated, if we pour a stratum of alcohol on the 

 surface, and if we prevent the formation of a cohe- 

 rent crust which impedes the contact of the liquids, 

 the whole of the ammoniated sulphate of copper, 

 while the deep blue solution becomes colourless, 

 because by the distribution of the alcohol through 

 the solution a mixture is formed, in which the salt 

 is insoluble. 



^ e rapidity of mixture of two liquids depends 

 by chemical on the degree of their chemical affinity; and the 



affinity, 



