294 Mr. T. Graham on Liquid Diffusion applied to Analysis. 



The experiments were all made through the same portion of 

 parchment-paper, and in the order of the Table — gum-arabic 

 first, and chloride of sodium last. After every experiment the 

 bulb was immersed in water for twenty-four hours, to purify the 

 septum, before it was again used. The diffusion of starch-sugar 

 was repeated early and late in the series of experiments, with 

 little change in the result, showing considerable uniformity in 

 the action of the parchment- paper, — the first diffusate of starch- 

 sugar being 2 grammes, and the second 2*13 grammes. Yet 

 the parchment-paper had been in contact with water or some 

 solution for a whole fortnight between the two observations 

 referred to. 



A layer of animal mucus, taken from the stomach of the pig, 

 12 millimetres in thickness (10 grammes of humid mucus being 

 spread over 0*005 square metre of surface), was applied, between 

 two discs of calico, to the diffusion-bulb used above, the parch- 

 ment-paper being first removed. 



Table XIII. — Dialysis through Animal Mucus during twenty- 

 five hours, at 10° to 15°. 



Ten per cent, solutions. 



Diffusate, in 

 grammes. 



Proportional 

 diffusate. 



Osmose, in 



grammes of 



water. 



Gum-arabic 



•023 

 1-821 

 1-753 

 1-328 

 1*895 

 2-900 

 1-765 

 2-554 

 5-054 



•004 

 •360 

 '347 

 •262 

 •375 

 •573 

 •349 

 •505 

 1 



+29 

 + 7-6 

 -f 4-6 

 + 7-1 

 + 5-0 

 + 7-2 

 4- 7-0 

 + 7-5 

 - 0-2 



Starch-sugar 



Cane-sugar 



Milk-sugar 



Mannite 



Alcohol 



Starch-sugar 



Glycerine 



Chloride of sodium 





The relative diffusibilities of the different substances present 

 a considerable degree of similarity in the two Tables, and are 

 equally analogous to the diffusibilities of the same substances 

 observed in pure water. The intervention of a colloid septum 

 cannot be said to have impeded much the diffusion of any of these 

 substances except the colloid gum. 



The dialysis through parchment-paper of several other organic 

 substances, both crystalloids and colloids, maybe brought together 

 in comparison with the chloride of sodium as a standard. The 

 larger osmometer bulb was used, and the parchment-paper was 

 now changed in each experiment. The substance in solution 

 amounted to 2 grammes, the depth of fluid in the dialyser to 10 

 millimetres (0*4 of an inch), and the surface of the septum to 

 0-01 square metre (15*6 square inches). 



