:212 Mr. T. Graham an Liquid Diffusion applied to Analysis. 

 Table II. — Diffusion of 10 per cent, solutions for fourteen days. 



No. of stratum 



Sulphate of 



Albumen, at 



Caramel, at 



(from above 



magnesia, 



13 d to 13°-5. 



10° to 11°. 



downwards). 



at 10°. 







1 



•007 







2 



•011 







3 



•013 







4 



•027 







5 



•049 







6 



•085 





•003 



7 



•133 





•005 



8 



•218 



•010 



•010 



9 



•331 



•015 



•023 



10 



•499 



•047 



•033 



11 



•730 



•113 



•075 



12 



1-022 



•343 



•215 



13 



1-383 



•855 



•705 



14 



1-803 



1-892 



1-725 



15 and 16 



3-G84 



6-725 



7-206 





10-000 



10-000 



10-000 



The sulphate of magnesia was anhydrous. The albumen was 

 purified by "NVurtz's method. The caramel was partly purified by 

 precipitation by alcohol, as recommended by Fremy, and further 

 by other means which will again be referred to. It will be re- 

 marked that the diffusion of sulphate of magnesia exhibited 

 above is very similar to that of sugar in a former Table, but is 

 slightly less advanced. The similarity in diffusibility of these 

 two substances had already been observed in the experiments of 

 former papers. The fall in rate on passing from these crystal- 

 loids to the colloids tannin, albumen, and caramel is very 

 striking. The elevation in the liquid column attained by albu- 

 men or by caramel is moderate indeed compared with that of 

 crystalline substances. Of albumen, which will be looked upon 

 with most interest, no portion whatever was found in the seven 

 higher strata. It appeared to the extent of 0*010 gramme in 

 the eighth stratum, 0-015 in the ninth stratum, 0*047 in the 

 tenth stratum, 0*113 in the eleventh stratum, 0*343 in the 

 twelfth stratum ; while the great mass of this substance remained 

 in the four lower strata. The diffused albumen did not appear 

 to lose its coagulability, or to be otherwise altered. It will be 

 seen immediately that the diffusion of sugar advances as much 

 in two days as the albumen above in fourteen days (Table IV.). 



The diffusion of caramel is the slowest of all, and does not 

 much exceed in fourteen days the diffusion of sugar in a single day. 



It was considered useful to possess examples of the progress of 

 diffusion, in one or two selected substances, for successive periods 

 of time, so as to exemplify the continuous progress of diffusion 



