.,
where a correspondent, in his albumen process, adds "chloride of barium, 7-1/4
dr." Now, as this article is prepared and sold both in crystals and in a
liquid state, it would be desirable to know which of the two is meant
before his disciples run the risk of spoiling their paper and losing their
time.

How easy would it be to prefix the letter _f_ where fluid oz., dr., or
other quantity is meant.

Trusting that this hint may in future induce your correspondents to be as
explicit as possible on all points, believe me to be an

AMATEUR PHOTOGRAPHER.

_Tent for Collodion._--As I have frequently benefited from the hints of
your correspondents, I in my turn hasten to communicate a very simple plan
I have contrived for a portable tent for the collodion process, in the hope
it may be found to answer with others as well as it has done with me: it is
as follows.

Round the legs of my camera stand (a tripod one) I have made a covering for
two of the sides, of a double lining of glazed yellow calico, with a few
loops at the foot to stake to the ground; the third side is made of thick
dark cloth, much wider and larger than to cover the side, which is fastened
at one leg of the stand to the calico. The other side is provided with
loops to fasten to corresponding buttons on the other leg, and by bending
on my knees I can easily pull the dark cloth over my head and back, fasten
the loops to the buttons, and then I can perfectly perform any manipulation
required, without the risk of any ray of white light entering; and
certainly nothing can be more _portable_.

The simplicity of the thing makes any farther description of it
unnecessary, to say nothing of your valuable space.

JAN.

_Mr. Sisson's Developing Solution._--The REV. MR. SISSON, in a letter I
received from him a few days ago, stated that he had been trying, at the
recommendation of a gentleman who had written to him upon the subject, a
stronger developing solution than that the formula for which he published
some time back in your pages, and that it gave splendid positive pictures
with very short exposure in the camera.

Since I received his letter I have been able to corroborate his testimony
in favour of the stronger solution, and have much pleasure in sending you
the formula for the benefit of your readers. It is this: 1-1/2 drachms of
protosulphate of iron in five ounces of water, 1 drachm of nitrate of lead,
letting it settle for some hours; pour off the cl