( 742 ) 
This photo-chemical decomposition might consequently be accelerated 
dst by taking an iodide more sensitive to light, and 2rd by decreasing 
the oxidation by silver nitrate (exposure with smaller light intensity). 
Both these conditions have been complied with in the extremely 
rapid photo-chemical decomposition of a-subiodide in weak twilight 
observed by me*’). 
Beside these reactions others set in, as the probable formation of 
iodates, oxidation through one of the reaction products of the chemical 
binding of iodine and silver nitrate, etc., the investigations into which 
are partly incomplete as yet. 
As subbromides and subchlorides oxidize far less rapidly, as is 
well-known, the deviations occurring in the case of subiodides, are 
much less likely to occur with them. 
Further a red subiodide of M. Carry Lea?) is well known, 
which, consequently, must contain a smaller amount of halogen than 
a-subiodide. 
Of the colour sequence of series (II) we accordingly know only 
green; en. red eht i thin: ee CEE 
The silver subbromides. In the following table the observations have 
been arranged in such a way, that D constantly increases. 
Agon Bron 
Fine-grained. Discoloration in daylight 
In gelatine. (October, 11 to 2 o’clock) 
(1). with 10°/, aqueous AgNO, sol. yellowish, reddish or 
brownish violet 
(2). with much H,O brownish violet 
(3). with little H,O red 
(4). moist reddish violet 
(5). less moist bluish violet 
(6). dry bluish 
Without binding substance 
(7). with KBr under ether, CCI, green 
These discolorations were not observed simultaneously, but always 
when the colour was most intense without passing into another. 
The decomposition takes place so unequally that, when exposed 
simultaneously, (1) and (2) already have a clearly perceptible colour 
after a few tens of seconds, whilst the others show hardly any 
visible decomposition. Compared with each other, the latter prepara- 
tions show little difference in the rapidity with which the colours 
appear. We see here a deviation from Lipro-Cramer’s observation 
