638 



PROCEEDINGS OP THE AMERICAN ACADEMY. 



For the Diffusion Constant of Silver Nitrate and the Metastable 

 Solubility Product of Silver Chromate in Gelatine at 16° C. 



IV. Results. 



Discussion of Results. — The values obtained for the diffusion constant 

 and for the metastable solubility product are constant within the limit of 



error of the method, as will be seen by a reference to the recapitulation 



x 

 of Table III. While the value of — z for any particular tube is constant 



Vt 



within one or two tenths of one per cent, the same good agreement is 

 not obtained when several series of observations are made upon different 

 tubes under as nearly as possible the same conditions. The mean devia- 

 tion of different tubes from the average is as great as one per cent. We 

 think this deviation can be accounted for by lack of uniformity in the 

 bore of some of the tubes, so that the diffusion takes place in a conical 



cavity instead of in a truly cylindrical cavity, as the theory requires. 



x 

 That an error of one per cent in the determination of — : will account for 



the variations in the values of a 2 and ^Tmay be seen by a glance at the 



result of a recalculation of these quantities from the data (d) and (e) of 



x 

 Table III, on the assumption that the correct value of — — in (e) is .0130 



Vt 



cm 2 

 instead of .0131 ; a 2 comes out to be 1.63 - — , and .ffbecomes 1.9 X 10 -6 . 



day 



x 

 Or, assuming — : to be .0132 instead of .0131, a 2 becomes 1.42 and H 



Vt 



becomes 0.7 X 10 -6 . 



