21 1 Mr. T. Graham on Liquid Diffusion applied to Analysis. 



found more useful in appreciating the diffusion of organic and 

 other less diffusible substances. In comparing the two Tables 

 together, it appears that a fourteen days' diffusion of sugar is 

 greater in amount than a four days' diffusion of chloride of so- 

 dium, but less than a five days' diffusion of the same substance. 

 The diffusion of chloride of sodium appears to be pretty nearly 

 three times greater (or more rapid) than that of sugar. 



The following experiments were made upon hydrochloric acid 

 and chloride of sodium at a somewhat lower temperature and for 

 times which are different, but which give a nearly equal diffusion 

 for each substance. 



Table IV. bis. — 10 per cent, solutions. 





Hydrochloric acid, 



Chloride of sodium, 



No. of stratum. 



in grammes. 



in grammes. 





3 days at 5°. 



7 days at 5°. ■ 



1 



•003 



•003 



2 



•006 



•009 



3 



•012 



•010 



4 



•022 



•026 



5 



•043 



•055 



6 



•086 



•082 



7 



•162 



•165 



8 



•308 



•270 



9 



•405 



•403 



10 



•595 



•595 



11 



•837 



•823 



12 



1-080 



1-085 



13 



1-163 



1-270 



14 



1-578 



1-615 



15 and 16 



3-699 



3-589 





10-000 



10-000 



The diffusion of hydrochloric acid in three days corresponds 

 closely with the diffusion of chloride of sodium in seven days. 

 The times of equal diffusion for these two substances, at the tem- 

 perature of the experiment, appear accordingly to be 1 (hydro- 

 chloric acid) and 2*33 (chloride of sodium). Hydrochloric acid 

 and the allied hydracids, with other monobasic acids, are the 

 most diffusive substances known. The general results of several 

 series of experiments may be expressed approximately by the 

 following numbers : — 



Approximate times of equal diffusion. 



Hydrochloric acid 1 



Chloride of sodium 2*33 



Sugar 7 



Sulphate of magnesia 7 



Albumen 49 



Caramel 98 



