76 M. C. Lea on the Action of Ozone upon 
tive to the diffuse light of the room. Such an error se 
however, unlikely. 
(5.) Paper was prepared as before, was exposed fifteen m 
[It was previously ascertained that a sensitized collodion plait” 
placed in the same position as respects the same light, was pow 
fully impressed in 20 seconds, or one-third the time just me 
tioned. ] a 
Paper was prepared in the same manner, but after plag 
in the solution of iodid, and washing, it was dried, and inti 
condition exposed to the ozone for fifteen minutes. Them 
the same gas light for one minute, partly covered. Result s 
as number 5. 
(7.) After treatment with silver and iodid, and washing, 
paper was exposed to ozone for fifteen minutes, then to the 
gas light as in (5) and (6) for one minute, partly covered. 
re 
been exposed to light, and those that had been produced 
thick yellow paper. * 
IL.—Action on Bromid of Silver. 
(8.) In order to give a greater variety to the experiments, ! 
bromid of silver submitted to trial was not disseminated thr : 
‘ y A. ay 
which the bromid of silver is suspended in the collodion wi 
sensibility destroyed by the presence of a small excess 0 
line bromid. The proportions used were as follows: 
ther, - - - - - + ounce. 
Alcohol, a . 0a ase. 
Pyroxyline, eos avec T BO game 
romid of ammonium, - . mie oe 
Nitrate of silver, - - - 134% 
These proportions leave a slight excess of bromid of 2 
hich ensures th 
nium present, which ensures that the bromid of silver is. 
insensitive form. shige ; 
(9.) A portion of this collodi oured on glass 
