89 
emer Bel toe we ot maar St 
in °C, : | minutes: | 50 ccm : lic Co. found: | gecomposed: 
22° + 1° 6 | 0. 150 0. 0567 | ie", 
id. eo | 1. 000 0.0546 45.8 
id. iel 1. 250 0.0411 Tan 
id. 60 | 1.500 0. 0475 | 26. 5 
id. 60 1. 750 | 0.0429 20.5 
id. 60 2. 000 0, 0465 19.5 
the mean decomposition in 60 minutes (ca. 0,0445 Gr. Co) is here only 
about *, of that formerly observed, — which may be chiefly caused 
by the fact, that the intensity of radiation of the quartz-lamp was 
a smaller one than formerly, and by asomewhat modified form of the 
vessels employed. All these measurements have, therefore, not an 
absolute, but merely a relative significance. 
§ 5. Results mutually agreeing much better, however, were obtained 
in the study of the influence, which the addition of certain electro- 
lytes to the solution has upon the photocatalysis under consideration. 
For it had soon become evident by preliminary experiments, that, 
— in contrast to VRANEK’s negative results of the addition of acids, 
— a remarkably strong influence on the speed of reaction could be 
observed, if neutral salts were added to the concentrated solutions of 
the cobalti-salt used by us. An addition of alcohol had, however, no 
appreciable effect; but solutions of neutral salts, if added to the 
photosensitive solution, have immediately a very distinct influence, 
when the salts of strong bases and acids are used for this purpose. 
Such acatalytic influence of salt-solutions on photochemical reactions 
has, indeed, been found already by some other authors, e.g. by 
JORISSEN and RricHer*) in the case of the photochemical oxydation 
of solutions of owalic acid by free oxygen, and by Rororr®) in the 
case of Eprr’s solution: the last mentioned investigator found even 
one case which seems to be of the same type as those described here. 
Subsequently the influence was studied by us, which resulted from 
the addition of varying quantities of potassiwm, sodium, and hthiwm 
chlorides ;. in a second series of determinations the analogous influence 
1) W. P. JorissEN and L. Tu. Reicuer, Zeits. f. phys. Chemie, 31, 142, (1899). 
*) M. Rororr, Zeits. f. phys. Chemie, 18, 327, (1894). 
