_Succinate of Iron Developer_.--I have received a letter from M.
Borlinetto, in which he states that he has been induced by the analogy
which exists between oxalic and succinic acids to try whether succinate
of iron can be substituted for oxalate of iron as a developer. To prove
this he prepared some proto-succinate of iron from the succinate of
potassium and proto-sulphate of iron, following the method given by Dr.
Eder for the preparation of his ferrous oxalate developer. He carried
out the development in the same way as is done by the oxalate, and
he found that the succinate of iron is even more energetic than the
oxalate. The plate develops regularly with much delicacy, and gives a
peculiar tone. It is necessary to take some fresh solution at every
operation, on account of the proto-succinate of iron being rapidly
converted into per-succinate by contact with the air.
_Method of Making Friable Hydro-Cellulose_.--At the meeting of the
Photographic Society of France, M. Girard showed his method of preparing
cellulose in a state of powder, specially adapted for the production of
pyroxyline for making collodion. Carded cotton-wool is placed in water,
acidulated with 3 per cent. of sulphuric or nitric acid, and is left
there from five to fifteen seconds; it is then taken out and laid on a
linen cloth, which is then wrung so as to extract most of the liquid. In
this condition there still remains from 30 to 40 per cent.
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