Mol. vol. 

 48 

 44 



? 



44 



Mr. J. J. Coleman on Liquid Diffusion. 9 



In regard to MendelejefFs 8th group, I have diffused ferrous 

 sulphate, cobaltous sulphate, nickelous sulphate, and cupric 

 sulphate, the molecular weights and volumes of which are as 

 follows : — 



Mol. wt. 

 Ferrous sulphate . . . . 152 

 Cobaltous sulphate . . . 155 

 Nickelous sulphate . . . 155 

 Cupric sulphate . . . . 159'4 



The diffusions were carried on fifty days at 10° C, 

 11 per cent, of the iron rose 100 millim. 

 10 „ „ cobalt „ „ 

 10 „ „ nickel „ „ 

 10 „ „ copper „ „ 



The diffusion rate of these substances, which closely approxi- 

 mates those of MendelejefFs 2nd group, the Dyads, also 

 corroborates the other experience as to the influence of the 

 molecular weights and volumes. 



The difference in diffusibility, however, between the first, 

 or Monad group of Mendelejeff, and his second, or Dyad 

 group, is very striking, and can be approximately represented 

 by the following figures : — 



Group I. Formula R 2 [Monads]. 







Sulphates. 



Nitrates. 



Chlorides. 



Lithium . . . 



12 



? 



? 



Sodium . . , 



15 



28 



34 



Potassium . . 



24 



33 



41 



Silver . . 



. . 17 



35 



insol. 



Average . .17 



32 



38 



Group II. Formula RO 



[Dyads]. 







Sulphates. 



Nitrates. 



Chlorides. 



Magnesium . 



. . 4 



21 



23 



Cadmium . 





. . 5 



? 



14 



Zinc 





3-5 



23 



23 



Mercury . 





6 



13 



10 



Calcium . 





insol. 



23 



27 



Strontium . 





ditto 



23 



27 



Barium . . 





ditto 



23 



27 



Average . . 5 21 21 



Mendelejeff classes cuprous salts with Monads; and it is 

 singular that very early in his experiments Graham pointed 



