Page 154 - The Wellington photographic handbook

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THE nature and the purity of the chemicals used for photo-
graphic purposes have a very great influence upon the
quality of the results obtained, an influence which many
photographers do not fully appreciate. In the case of some of
the chemicals employed, there is also a risk that, owing to the
rather loose way of naming them, there may be a misunderstanding
as to the precise substance that is meant. To guard against both
these risks as far as possible, the following list, which contains
most of the chemicals referred to in the foregoing notes, arranged
in alphabetical order, has been prepared. Against each such
particulars as it is desirable that the photographer should know
have been given.
Before making up any formula in the preceding pages, there-
fore, its components should be turned up in the list.
Where it is stated that a substance keeps well, it is assumed
always, unless the opposite is stated, that it is kept in a properly
The only obvious exception that might be made
stoppered bottle.
to this rule, is the case of hypo ; and even hypo keeps better, with
less risk of impurity, in a corked jar than loose in a paper bag.
Before any liquid is applied to a plate or paper, it is most
important to see that all the ingredients are completely dissolved.
Minute particles of amidol, metol, etc., undissolved in a developer
cause black spots. Fine particles of developer dust, pyro, metol,
amidol, etc., floating in the air of the work-room, also give rise to
spots if they settle on any sensitive plates or paper.
All WELLINGTON Chemicals are tested for photographic
suitability before being placed on the market. They may be
relied upon to be of the highest quality obtainable and the worker
can employ them with absolute certainty that none of his results
will suffer by their use.
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