A simple test to discriminate between Sodium Sulphite and Sodium Carbonate is as follows: If a crystal of the salt is dissolved in a little water and a drop or two of sulphuric acid added to the solution, there will be a brisk effervescence, but there will be no smell to the gas that is given off if the substance is sodium carbonate. If it is sodium sulphite there may be a slight effervescence, but the liquid will smell strongly of sulphurous acid, the odor of a burning match.

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FROM AN ARTURA IRIS PRINT

By Edward H. Weston Tropico, Cal.

A Simple Test StudioLightMagazine1916 154

It's remarkable how children out-grow their smocks and frocks, their playthings, their childish ways, and - most of all - their photographs.

Only photographs will keep them as they are.

Make the appointment to-day

THE PYRO STUDIO

The 1916 Kodak Advertising Competition $3,000.00 CASH for pictures best illustrating Kodak Advertising

Can't you think of a picture that will help sell Kodaks, one that will forcibly illustrate the pleasures of photography? And can't you put your idea in a print?

The experience will be worth while and the ten prizes offered, ranging from $1,000.00 to $100.00, provide a generous incentive.

Write for circular giving full details.

Entries from Canada should be sent to the Canadian Kodak Company, Toronto, Canada, before October 20th, 1916.

EASTMAN KODAK COMPANY, Rochester, N. Y.

A Simple Test StudioLightMagazine1916 155

FROM AN ARTURA IRIS PRINT

By Clarence Stearns Rochester, Minn.

Know Your Fixing Bath

One can't become too intimately acquainted with the peculiarities of the ordinary acid fixing bath, especially during the hot summer months. There is no better, cleaner-working fixing bath for developing-out papers, and there is no one photographic solution that is more abused. As a consequence a large portion of the ills to which a photograph is heir may be traced to the fixing bath.

The acid fixing bath keeps the print hard and firm, stops development immediately, prevents developer stains and fixes the print if the bath is properly made and is in good condition.

One of the principal causes of trouble is the worn-out bath which remains clear even after it has been used for as many prints as the hypo in the solution can be depended upon to fix thoroughly. Sixty-four ounces of the

regular Artura Fixing Bath should never be used for more than the equivalent of two gross of cabinet prints which would be approximately six dozen 8 x 10 prints. This does not apply to Artura alone but to all developing-out papers.

Nothing is more uncertain than an improperly fixed print. It attacks your reputation in an underhanded way - stabs it in the back, as it were - and you learn of the injury too late to use first aid measures. The print may look all right when it leaves your hands, but after the customer has had it for some time it begins to look sick.

The highlights yellow first and if it has had very little fixing the entire print may discolor. Keep an account of the number of prints your bath has fixed and make a fresh solution as soon as it nears the danger point, which should be while the bath is perfectly clear.

There are many other causes of trouble, the first of which may be in compounding the bath. The most approved method is to make a stock solution of hardener and make up a fresh fixing bath every day or for every batch of prints.