Scheikunde. De Heer Ernst Cohkn hiedl eene mededeeliiig- aan 
van den Heer Nii, Ratan Dhar (with A. K. Datta and 
D. N. Bhattacharya) ; ,,Cataly.n.‘i VIII”. 
(Mede aangeboden door den Heer Van Romburgh). 
a. Reaction betweeu. silver nitratt- and ferrous-animoninm mlpkate 
I tried to deterniine the kinelies of (he reaetion l)etween ferrons 
ammonium sulphate and silver nitrate. The reaetion seems to be 
very rapid. 
When silver nitrate and ferrons ammonium sulphate are 
mixed at 25°, a himoleeular veloeitj coëfficiënt of 0.0007 is obtained, 
but unforinnately this coëfficiënt falls off as the Chemical reaetion 
l>roceeds. Since the metallic silver foi'uied reacts on the ferric salt 
jiroduced and we get au equilibi'ium of this nature 
2 Ag + Fe, (SOJ, Ag.,S(), -f 2 FeSO, 
Ag + Fe (NO,), AgNO, + Fe (NO,), 
(Fe++) (Ag+) 
or — at equilibrium = 00 28 
Fe-b+H- 
(cf. Noyes en Braun, .Jour. Amer. Chem. Soc. 1912, 34, 1016) the 
reaetion betweeii ferrons ammoidum sulphate and siher nitrate is 
rapid even at 0° and lias a small value for its temperature coefiicient. 
The reaetion is maikedly accelerated by acids; intric, sulphuric, 
citric, tartaric, and acetic acids have been tried ; the greater the 
concentration of hydrogen ions, the greater is the velocity. This 
catalytic activity may lie utilised in detei'mining the concentration 
of hydrogen ions. 
Magnetic force has practically no effect on this reaetion. It is 
extrernely sensitive to the influence of dirt etc. 
Potassium nitrate apfueciably retards the reaetion, so do manganese 
salts very marJ^edly. 
Carbonic acid markedly accelerates the reaetion. Boric acid is 
liractically without any influence. So is phenol, which is probably 
slightly retarding in its effect. Glucose markedly accelerates the 
reaetion. This is a case of induced reaetion. A mixture of excess of 
silver nitrate and very little of ferrons ammonium sulphate was 
prepared and divided into equal parts, to one of which glucose was 
