THE ACTION OF ORGANIC PEROXIDES ON THE 

 PHOTOGRAPHIC PLATE. 



By Bexjamin T. Brooks. 

 (From the Chemical Laboratory, Bureau of Science, Manila, P. I. 



With the recent- development of our knowledge of radioactivity, the 

 action of many substances on the photographic plate has been studied 

 and in some cases this property has been taken as a test for radioactivity. 

 This property alone is not sufficient to characterize a bo'dy as being 

 radioactive, as is ver}' generally recognized. jSTevertheless papers still 

 continue to find their way into the chemical literature ascribing radio- 

 activity to certain substances which aifect the photographic plate but 

 which have little or no semblance to the heavy metals. 



That the "pseudo-radioactive" substances are not radioactive in the 

 same sense as the heavy metals has been shown b)' Russell, Saeland and 

 Ebler. 



Kussell ' has described recently the action on the photographic plate of 

 colophony and a number of substances which contain resin. He has shown that 

 the shadows thrown by resin are not bounded by straight lines, but curve round a 

 screen ; that the action is not capable of passing through glass, mica, or aluminium 

 foil, even of extreme thinness, and does not affect an electrical field. The action 

 can pass along a bent glass tube, and may be swept out of a tube by a slow current 

 of gas. No action takes place in an atmosphere of carbon dioxide. Heat destroy3 

 the activity and previous exposure to sunlight accelerates it. Alkalies or sulphur 

 dioxide destroy the activity. When the activity of a specimen is destroyed by 

 any of the above means, exposure to o.xygen and light restores it. Russell also 

 prepared crystalline abietic acid and found it to be active. Turpentine and 

 specimens of pure pinene and limonene after exposure to air showed the same 

 behavior. A similar behavior of linseed oil is described by him - in a previous 

 communication. 



Russell states that the effect appears to be produced by a vapor rather than 

 by any form of radioactivity. He had previously shown * that the vapors of 

 hydrogen peroxide affect a photographic plate, even in dilutions of one part in 

 a million. He suggests that this may be the active substance. 



Saeland * has recently shown that the action on the photographic plate of the 

 alkali metals, magnesium, zinc and other metals which have a high solution 



^Proe. Roy. Soc. Lond. (1908), B, 80, 376. 

 ^Proc. Roy. Soc. Lond. (1898), 63, 102. 

 ^Proc. Roy. Soc. Lond. (1899), 64, 409. 

 'Ann. d. Phys. (1908), 26, 899. 

 90339 8 451 



