DNA AND Effects of Radiation and Peroxides 277 



(ii) Crystallized disuccinoyl monoperoxide (Formula II), 

 synthesized in this laboratory by R. Royer and B. 

 Ekert. This is in the form of prismatic colourless 

 crystals, which melt at 128° C, and explode weakly and 

 without danger in a flame. They are water-soluble at a 

 concentration by weight of 10"^, and are very stable in 

 the dark and in dry air. This compound is immediately 

 hydrolysed when dissolved in water, yielding one 

 molecule of succinic acid and one molecule of succinic 

 peracid, which is in fact the active principle of the 

 solution. 



CO — CH,— CHf-COOH 



I 



oh'"'"o' 



CO— CHj— CH^— COOH 



Formula II 



The solution, in the dark at room temperature, liberates 

 about 5 per cent of its peroxidic oxygen per day. All solutions 

 were titrated for peroxide activity by Mr. B. Ekert. The 

 cumene peroxide was titrated by the thiofluorescein method 

 (Dubouloz, Monge-Hedde and Fondarai, 1947); the succinic 

 peroxide was titrated by oxidation of ferrous iron and spec- 

 trophotometric dosage (302 my.) of the ferric iron. Precision 

 reached 2 pig. of peroxide per ml. 



R 



In some respects, the — C — O — OH function of the cumene 



i • 



O 



compound differs from the — C — O — OH of the succinic com- 

 pound. While many similarities were observed, striking dif- 

 ferences sometimes appeared in their action on the biological 

 samples. Cumene peroxide does not render the solution acid, 



