Photography has advanced rapidly, but as materials have been improved and processes simplified, some of the important chemical reactions that do not change have come to be slighted or their importance minimized.

However plates and papers may be exposed and developed, they are still fixed in the same old way, but often with less knowledge of what really takes place in the fixing process.

Washing is looked upon by many as of greater importance than fixing - but such is not the case. More harm can result from short fixing, using a worn out fixing bath or one that has become too warm, than by short washing.

A certain amount of hypo will clear a certain number of negatives, but there must be an excess of hypo to remove the silver from the gelatine emulsion. The first or clearing action of the hypo forms a silver salt which is insoluble. With continued fixing this turns to a soluble salt which leaves the film.

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Copyrighted by Emma B. Freeman Eureka, Cal.

This applies to paper as well as plates. If a fixing bath is almost worn out, the insoluble salt may be formed, but if there is not enough hypo to continue the fixing process and form the second salt, which dissolves and leaves the emulsion, the print or negative will in a short time begin to show stains. And no amount of washing after incomplete fixing will remove the insoluble silver salt which is the cause of this stain. The only preventive (there is no "remedy") is a fresh fixing bath that should always be discarded before it is worn out.

If a paper fixing bath becomes too warm the prints may tone while fixing, or if they do not actually change color in fixing and are allowed to mat together in the washing, they may change color there or even after they are laid out to dry.

Impure Sulphite of Soda containing sulphate or sulphite that has been exposed to the air causing sulphate to form, will cause a fresh fixing bath to become milky, indicating that sulphur has been released from the hypo. This will cause prints to tone in fixing, the action being known as sulphurization. Never use a fixing bath that is milky.

Negatives or prints are not injured by remaining in a good fixing bath for a longer time than is required for fixing, but they may be injured by long washing in hot weather. The fixing bath contracts the gelatine emulsion and expels the water, leaving the gelatine dryer and harder than when fixing began. On the other hand, long washing in water that is slightly warm softens and swells the emulsion and may cause frilling and other similar troubles.

In warm weather negatives are better for fixing longer than is necessary in a fresh bath. Thirty minutes fixing is not too long, if the negative clears in eight or ten minutes, while twenty minutes washing in running water will be ample.

When quantities of prints are fixed at one time in a fresh bath, fixing should be longer than for a small number, as it is not possible to keep them all separated all the time they are in the solution. They should also be washed longer than plates, because the fixing chemicals must be removed from the paper as well as the emulsion.

Never attempt to renew a fixing bath by merely adding hypo. The result is an unbalanced solution which will not properly fix. Make up a new bath.

The simplest way to make a fixing bath is to have a hardener in stock solution. Then it becomes a simple matter to dissolve the proper amount of hypo in water and add the hardener, after being sure the hypo is thoroughly dissolved.Retain all the sparkle of highlights - all the delicacy of half-tones by using

EASTMAN PORTRAIT FILMS

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Copyrighted by Emma B. Freeman Eureka, Cal.

Telephone us for an appointment. We will be glad to make portraits - in your own home - of the children, yourself, the entire family or any gathering of friends. The charm of home surroundings adds immeasurably to such pictures.

THE PYRO STUDIO

Bell 1243 Home 248

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No. 215. Price, 30 cents.

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ARTURA PRINT FROM SEED PLATE NEGATIVE

By Clifford Norton Cleveland, Ohio