THE PHYSIOLOGICAL EFFECTS OF IONS 473 



the protoplasm, and consequently its osmotic pressure, is 

 affected differently by the different ions of which we will 

 say more immediately the agreement between the values is 

 satisfactory enough for proving the validity of Van 't Hoff's 

 theory of osmotic pressure for the life phenomena of cells. 

 Barium chloride, however, seems to be an exception. 



VII. ON THE EFFECT OF POTASSIUM CARBONATE AND SODIUM 

 CARBONATE SOLUTIONS UPON THE MUSCLE 



If solutions of Na 2 CO 3 and K 2 CO 3 of the same concen- 

 tration as a 0.7 per cent. NaCl solution are prepared, muscles 

 immersed in them increase markedly in weight. Table XV 

 gives the increase in weight of the muscles in these solutions 

 after one hour. 



TABLE XV 



The muscles showed the glassy appearance of a muscle 

 which has been in a weak solution of an alkali. The order of 

 magnitude of the absorption of water also corresponds with 

 the effects of an alkali. According to the theory of dissocia- 

 tion, this effect is brought about in the following way: The 

 potassium carbonate is dissociated in part into potassium and 

 CO 3 ions; as carbonic acid is a very weak acid that is to 

 say is only slightly dissociated each CO 3 ion combines 

 with two H ions to form carbonic acid. Two negatively 

 charged OH ions must, in consequence, go into solution, 1 and 

 these bring about both the alkaline reaction of the solution 

 and the absorption of water by the muscle. We are dealing 

 in this case, therefore, not with potassium or carbonate 

 effects, but with the effects of hydroxyl ions. 



1 More correctly form 2KOH, which, however, at this degree of dilution is dis- 

 sociated to a high degree. [1903] 



