II4 THE NORTHERN MICROSCOPIST. 
powerful light. At the same time, I did not use bare sunlight, 
which, as is well known, gives not only hard pictures, but pictures 
rendered defective by interference phenomena. I allowed the sun- 
light to pass through an ammoniacal solution of copper rendered 
as monochromatic as possible, and then diffused and softened it by 
allowing it to pass through ground glass. ‘To this I attribute, in 
the main, the sharpness and purity of my pictures. Using diffused 
sunlight through ground glass in this way, I find that an exposure 
of about two minutes suffices in the case of an enlargement of 
seven hundred times. 
“Of course, with gelatine, I shall be able to make shorter 
exposures, and I am just now engaged in making test experiments 
relating to its sensitiveness. I am also testing gelatino-bromide in 
respect to its sensitiveness in particular for violet and blue light, 
as also for green and yellow, my object being to see how far I can 
photograph preparations stained blue; for in pathology and 
histology the microscopic preparations are, for the most part, of 
this tint. The question of colour enters also largely into the 
matter when bacteria are to be reproduced ; but I have little doubt 
that the gelatino-bromide process will lighten the labour of the 
micro-photographer very considerably.” 
NORTHERN SOCIETIES. 
BOLTON Microscopicat Society. Hon. Sec.: Mr. W. Rideout. Meets on Friday 
evening once in each month. 
CHESTER Naturat ScIENcCE ASSOCIATION. Hon. Sec. of Microscopical Section: 
Mr. J. D. Siddall. 
DONCASTER MyicroscoricaL Society. Hon. Sec.: Mr. M. H. Stiles. Meets 
twice in each month 
HALIFAX. A Private Society. Members meet at each others houses. 
LEEDS. No Microscopical Society in existence. 
LIVERPOOL MicroscopicaL Society. Hon. Sec.: Mr. I. C. Thompson. Meets 
First Friday in each month 
MANCHESTER Mricroscopicat Society. Hon; Sec.: Mr. C. L. Cooke. Meets 
First Thursday in each month. 
MANCHESTER Cryprtocamic SociETy meets Third Monday in each month, at Old 
Town Hall, King Street. 
MANCHESTER Science AssocraTIon. Hon. Sec.: Mr. J. Percival Yates. Meetings 
Second and Fourth Tuesday in each month. 
NEWCASTLE-ON-TYNE. Norrtu oF ENGLAND Microscoricat Soctety. Hon. 
Sec.: Mr. M. H. Robson. Meets Second Wednesday in each month. 
NOTTINGHAM Literary aND PHILOSOPHICAL Society. Natural Science Section 
hold meetings Fortnightly on Wednesdays. Hon. Sec.: Mr. A. H. Scott 
White, M.A. 
OLDHAM Microscopicat Society. Hon. Sec.: Mr. Charles Walters. Meets on the 
Third Thursday of each month, in the Club-room of the Lyceum. 
ROCHDALE AND say Piatt MicroscopicaL Society. Hon. Sec., Mr. I. 
Renshaw, L.D.S.R.C.S. 
SHEFFIELD. No Microscopical Society in existence. 
