INFLUENCE OF LIQUIDS UPON OSMOTIC CURRENTS. 489 



the properties of the liquids must have an important in- 

 fluence upon osmose, both from differences in the attrac- 

 tion of the membrane for the liquids, and their different 

 degrees of diffusibility. In order to appreciate fully all the 

 physical phenomena of osmose, it will be necessary to study 

 carefully the laws of diffusion of liquids and the diffusibility 

 of different solutions ; but it will be sufficient for our present 

 purpose to state a few general propositions, which will be 

 fotind more or less applicable to physiological absorption. 



When two liquids, capable of mixing with each other, 

 are brought together, they diffuse with greater or less rapid- 

 ity, until the constitution of the mixture becomes uniform. 



Different liquids possess widely different degrees of diffu- 

 sibility ; and as a rule, in saline solutions, the rate of dif- 

 fusion increases in proportion to the strength of the solution, 

 at least when the quantity of salt dissolved does not exceed 

 four or five per cent. 1 It follows from this that the activity 

 of the endosmotic current toward any saline solution will be 

 greatest at the beginning of the experiment, and will pro- 

 gressively diminish as the currents continue and the two 

 liquids assume a more nearly uniform density. 



The rate of diffusion of different solutions is generally 

 increased by a moderate elevation of temperature. 



Bearing in mind these general laws, and remembering 

 that they are applicable to diffusion as it takes place through 

 animal membranes, we can easily understand how different 

 liquids and solutions, in an endosmometer, will attract with 

 different degrees of intensity any given liquid, such as pure 

 water ; and how this attractive force, which is measured by 

 the rapidity and extent of the rise of liquid in the endosmom-. 



1 GRAHAM, Elements of Inorganic Chemistry, Philadelphia, 1858, p. 743. 



The diffusibility of different acid and saline solutions has been very fully in- 

 vestigated by Graham, who has developed many interesting facts showing the 

 influence of different liquids upon osmotic phenomena. For further information 

 on this subject, the reader is referred to the papers published by Graham in the 

 Philosophical Transactions, in 1849, 1850, and 1857 ; and to the chapter on "Dif- 

 fusion of Liquids," in the Elements of Inorganic Chemistry, by the same author. 



