Mr. T. Graham on Liquid Diffusion applied to Analysis. 221 



of sodium, when the mixtures are in a state of solution. With 

 two acids very unequal in their affinity for bases, the result pos- 

 sibly might be very different. 



Table X. — Diffusion of a mixture of 4*01 per cent, of Chloride 

 of Sodium and 5*99 per cent, of Sulphate of Potash (equiva- 

 lent proportions), for seven days, at 14°. 



No. of stratum. 



Potassium, 



Sulphuric acid, 



Total diffusate, 





in grammes. 



in grammes. 



in grammes. 



1 



•028 



•002 



•023 



2 



•034 



•002 



•030 



3 



•049 



•004 



•044 



4 



•064 



•009 



•065 



5 



•092 



•015 



•096 



6 



•128 



•031 



•149 



7 



•172 



•059 



•219 



8 



•242 



•104 



•315 



9 







•435 



10 







•600 



11 







•797 



12 







1-025 



13 







1-261 



14 







1-480 



15 and 16 







3-467 







10-016 



2. Effect of Temperature on Diffusion. 



Diffusion is promoted by heat ; and separations may accord- 

 ingly be effected in a shorter time at high than at low tempera- 

 tures. In a series of observations made upon hydrochloric acid, 

 the diffusion of that substance was carefully determined at 15°*5 

 (60° F.), and at three higher points, advancing by 11°*11 

 (20° F.). The ratios of the diffusions observed were as follows : — 



Diffusion of hydrochloric acid at 15°-55 ( 60° F.), 1 



at 26°-66 ( 80° F.), 1-3545 

 at 37°*77 (100° F.), 1*7732 

 at 48°*88 (120° F.), 2*1812 



The increments of diffusibility, 0*3545, 0*4187; and 0*408 for 

 equal increments of temperature, are probably affected by small 

 errors of observation, but they appear to indicate that the diffu- 

 sion increases at a higher, although not greatly higher, rate than 

 the temperature. The average increase of diffusibility for the 

 whole range of temperature observed is 0*03543, or ^ for each 

 degree (0*01969, or -^ nearly for 1° F.). 



The preceding experiments were made by diffusing a 2 per 



