982 



this acid diffused was determined with great exactness by neutrali- 

 zation by means of a normal solution of carbonate of soda. 



The diffusion of the different proportions of this acid at one tem- 

 perature is as follows. 



Diffusion of nitrate of water in five days at 51°'2 ; two cells: — 



Grs. Ratio. 



From 1 per cent, solution 6*99 0*95 



From 2 per cent, solution 14*74< 2 



From 4 per cent, solution 28*76 3*90 



From 8 per cent, solution 57*92 7" 86 



The 2 per cent, solution is taken as the standard of comparison 

 for the ratios, instead of the 1 per cent, solution, from the greater 

 accuracy with which the diffusion of the former can be observed. 



The usual approach to equality of diffusion, between chlorides 

 and nitrates, is observable in hydrochloric and nitric acids, at least 

 in the 1 and 2 per cent, solutions. 



Sulphuric Acid. — The time of diffusion arbitrarily chosen for this 

 and the three following acids was ten days. The diffusate of this 

 acid was determined in the same manner as that of nitric acid. 



The diffusion of the different proportions of sulphuric acid is as 

 follows. 



Diffusion of sulphate of water in ten days at 4'9°*7 ; two cells : — 



Grs. Ratio. 



From 1 per cent, solution 8'69 1*03 



From 2 per cent, solution 16*91 2 



From 4 per cent, solution 33*89 4*01 



From 8 per cent, solution 68*96 8*16 



The diffusibility of different strengths of this acid appears to be 

 pretty uniform, but with a slight tendency to increase in the higher 

 proportions, like hydrochloric acid. 



Sulphuric acid is greatly inferior in velocity of diffusion to hydro- 

 chloric acid, but still appears to possess considerably more than half 

 the diffusibility of the latter. 



Chromic Acid. — The diffusate of the 2 per cent, solution was 

 22'43 grs. of chromic acid, in two cells, at 67°*3. The diffusion of 

 sulphuric acid at 63°*5, was 19*73 grs., which would give about 

 21 grs. of that acid at 67°*3. 



Acetic Acid. — This acid cannot be determined accurately by the 

 acidimetrical method, owing to the acetates of potash and soda being 

 essentially alkaline to test-paper, like the carbonates of the same 

 bases, although neutral in composition. The weight of carbonate 

 of baryta dissolved by the acid was had recourse to. 



Diffusion of acetate of water in ten days at 48°*8 ; two cells : — 



Grs. Ratio. 



From 2 per cent, solution 11*31 2 



From 4 per cent, solution 22*02 3*83 



From 8 per cent, solution 41*80 7*26 



The diffusibility diminishes with the larger proportions of acid. 



