274? Prof. Graham on the Diffusion of Liquids, 



same manner, and I shall now add a third series of results 

 obtained from the diffusion of 1 per cent, solutions of the same 

 salts. The temperature of diffusion of this new series was 

 64°* 5. Six phials of each salt were diffused, and they were 

 evaporated afterwards two and two. This double diffusion 

 product, however, is divided by 2 in the table. 



Diffusion of Salts of the Nitre Class. 





4. 



2. 



1. 



Nitrate of potash 



13-97 

 14-48 

 1501 

 14-41 

 13-31 



7-47 

 7-73 

 7-70 

 7-81 

 7-22 



3-72 

 3-75 



3-88 

 3-89 

 3-66 





Chloride of potassium 



Chloride of ammouium 



Chlorate of potash 





Mean 



14-23 



7-58 



3-78 





It is interesting to observe how the chlorate of potash rises 

 in the lower proportions and approaches to the normal rate 

 of its class. The diffusion products of all the salts are obvi- 

 ously more uniform for the two than for the 4 per cent, solu- 

 tions, and again more uniform for the 1 than for the 2 per 

 cent, solutions. The extremes in the 1 per cent, solutions 

 are 3*66 grs. chlorate of potash, and 3*89 grs. chloride of am- 

 monium, which are as 1 to 1*0628. We have here an ap- 

 proach to equality in diffusion, which appears to be as close 

 as the experimental determinations are of the specific heat of 

 different bodies belonging to one class. The numbers for the 

 specific heat of equivalents of the metallic elements are known 

 to vary as 38 to 42. 



The salts of potash thus appear to fall into two groups of 

 very similar if not equal diffusibility. What is the relation 

 between these groups ? 



The diffusion of 4 per cent, solutions of carbonate and ni- 

 trate of potash was repeated at a temperature rising gradually 

 from 63° to 65° during the seven days of the experiment, with 

 a mean of 64°*1. The diffusion products of the carbonate 

 were 10*31, 10*05 and 10*44 grs. in three cells; mean 10*27 

 grs. Of the nitrate, 13*98, 13*86 and 13*60 grs. ; mean 13*81 

 grs. We have thus a diffusion in equal times of — 



Carbonate of potash . . 10*27 1 



Nitrate of potash . . . 13*81 1*3447 



These experiments are almost identical with the former re- 

 sults, 10*25 carbonate of potash, and 13*97 nitrate of potash. 

 But the numbers thus obtained cannot be fairly compared, 

 owing to the diminishing progression in which the diffusion of 



