54 REPORT—1862. 
On Hypobromous Acid. By Prof. H. E. Roscoz. 
Professor Roscoe communicated to the Section the results of an investigation 
upon the lowest oxide of bromine, hypobromous acid, which had been made in the 
iabarsbeee of Owens College, Manchester, by Mr. William Dancer. Balard in 
1826 mentions the formation of a colourless bleaching salt formed by the action of 
bromine upon the alkalies, and since that date many chemists have indicated the 
resence of such a body, but it has not been prepared in a pure state or analysed. 
Mir. Dancer has succeeded in preparing the aqueous acid in a pure state, and has 
examined its chief properties and determined its composition. If bromine-water 
and nitrate-of-silyer solution be brought together, one-half the bromine is precipi- 
tated as bromide of silver, whilst the other half remains in solution as hypobromous 
acid (BrOHO). The aqueous acid may be obtained by distillation at 30° C. in 
vacuo, but decomposes into bromine and oxygen at 100° C. The aqueous acid may 
likewise be prepared by shaking bromine-water together with oxide of mercury, 
and distilling 7m vacuo; in this case half the bromine hte the bleaching compound. 
Hypobromous acid unites with the alkalies, and forms salts analogous in smell and 
bleaching properties to the corresponding hypochlorites. Owing to the ease with 
which this compound splits up into bromine and oxygen, it was found impossible 
to prepare the hypobromous anhydride by any of the methods used for the isolation 
of the corresponding chlorine compound. 
Description of a rapid Dry-Collodion Process. By T. Surton, 
A rapid dry-collodion process, by which dry plates can be prepared as sensitive as 
with wet collodion, has more than any other problem interested photographers. 
By the wet process, the negative has to be finished on the spot, The rapidity of 
this dry process depends upon the effect of bromine in dry collodion. In the 
Daguerreotype process a silver plate iodized is extremely insensitive, but when sub- 
mitted to the fumes of bromine it is increased a hundredfold. In the wet, but not 
in this process, nitrate of silyer is required, which is the element of instability. 
In preparing, therefore, rapid dry-collodion plates, bromo-iodized collodion must be 
used, But the image produced thus is extremely thin and superficial ; it is there- 
fore necessary to apply to the film a coating of some organic substance, in order 
to darken parts of the negative. Many substances have been tried for this purpose, 
but none produce so good an effect as gum-arabic, The paper concluded with the 
operations required for this process. 
GEOLOGY. 
Address to the Geological Section by J. Brrte Juxus, M.A., F.R.S. 
It is now thirty-two years ago since I first, when a “freshman” of this Univer- 
sity, attended the geological lectures of Professor Sedgwick. I had previously 
had access to a cabinet of fossils, and had been accustomed to seek for specimens 
in my schoolboy rambles on the hills near Dudley. It may be imagined, therefore, 
with what interest I listened to the “winged words” of the Woodwardian Pro- 
fessor, which used day after day to delight an audience composed of all ranks of the 
University. 
Geology and its kindred sciences did not then, indeed, form any part of our re- 
gular course of university studies, and many of the college tutors were so far from 
encouraging our attention to them, that they rather discountenanced it, considering 
them as at best useless and probably even dangerous pursuits. With such a man 
as Professor Sedgwick, however, in the Woodwardian chair, whose wit and humour 
delighted, while his eloquence aroused and informed his hearers, the love of the 
science and the knowledge of it could not fail to extend from one year to another. 
The natural sciences are now considered as worthy of study, by those who haye 
a taste for them, both in themselves and as a means of mental training and disci- 
