with water, thus stopping development. It also
leaves sufficient margin in the event of over- or under-exposure. With one
minute as the unit, over-exposure will result in a fully developed image
in, say, thirty seconds. This print we could save; but if our unit were
thirty seconds it would be extremely difficult to save a print which had
completed development in fifteen seconds. The chances are that the
development would go on to a ruinous extent before we could pour off the
developer and flood the print, or that it would go on even after the water
was poured on it. Moreover, in case of under-exposure, two minutes would
not be so very tiresome, but four minutes would, besides which we would
risk straining the print by such prolonged development. While I am not
prepared to assert it as a rule, yet it has been my experience that the
time of development varies almost inversely with the length of exposure;
so that if the test-strip concludes development in half a minute with ten
seconds exposure, I give the next five seconds exposure in the expectation
that it will take a minute to develop. This assists greatly in lessening
the number of test-strips required to ascertain the correct exposure of a
given negative.

Should we wish to see a proof before the negative is dry, it is taken from
the fixing bath and well rinsed, though not necessarily thoroughly washed.
It is then placed face up in a tray of water, on which we place face down
a sheet of bromide paper. The two are removed together and squeezed
lightly into contact to remove air bubbles. The back of the negative is
then wiped to remove superfluous water, and an exposure of several times
the normal given, preferably the normal exposure at half the standard
distance from the light. The paper is then removed and developed as usual.
In this way it is possible to show a print in fifteen or twenty minutes
after the exposure of the plate was made.

The purpose of the rinsing before development is to avoid the possibility
of air-bells. The paper should be rinsed in cold water, as warmish water
will cause air-bells instead of preventing them. This rinsing can be
dispensed with if thought desirable. The rinsing after development is for
the purpose of stopping development immediately, and also in order that
the prints may not go into the fixing bath full of developer, as staining
would be likely to result in such case. With the iron oxalate developer an
acid rinsing bath is neces