a 417 
ocess for the reduction of — waste has been discovered ” 
ae and CoMMAILLE mo promises be of practical value. 
the fact first observed by these chemists, that sich 
subchlorid of copper precipitates completely perfectly pure silver from 
a solution of nitrate of silver to which a slight excess of ammonia has 
been added. In the first ae the ammoniacal subchlorid of copper 
is prepar red by dissolving 5 parts of black oxyd of copper and 4 parts 
of finely divided metallic copper in chlorhydric acid. When the whole 
is dissolved, an excess of the strongest liquid ammonia is added, which 
pour n exce 
and collect, ee and dry the pure reduced silver, The same reagent 
may also be used for reducing the silver of an old hyposulphite bath, 
only in ‘Sond ugpihg this process it is important to observe ie following 
precautions: Ist, not to add too much ammonia; 2d, to the mix 
ture greatly diluted; 3d, to allow sufficient time for the fing: mein 
particles to soy completely to the bottom.—JZondon Journal of Pho- 
tography, x, 2 
8. Sulphocyanid of ammonia as a fixing agent.—Experiments have 
been made by G. W. Simpson and Mr. Le tnt on sulphocyanid of 
© Année, No. 5, p. 35, ‘and No. 7,p.5 
9. Redeve evelopers-— —(a.) Mr. Peiaoaab: recommends for redeveloping 
negatives 
Green vitriol, . Sa ° 1 A, davai 
Citric acid, ie « 
Water, 100 - 
_ This intensifier is used si like th e ‘i Hlie acid solution, adding to 
it a small man i val utio: 
n of nitrate o Pairer, and pouring it on the 
negative alre: ped with the usual iron developer. The advan- 
tages aa i er pn att acid are that the solution keeps better 
