Photographic chemicals are not known to be absolutely correct for the purpose intended until given an actual test and analysis.

Take sodas for example. Sodium sulphite may originally be high grade and full strength but, due to atmospheric conditions, may deteriorate and become decidedly low grade before reaching the hands of the photographer. In such cases the action is of course affected and it becomes practically worthless. Sulphite becomes sulphate and sulphate is not a preservative. Therefore low grade sulphite does not act as a preservative as it should.

In other cases deterioration not only destroys the originally intended function of the chemical but when the chemical thus affected is employed a harmful reaction may be set up causing unlooked for results in the finished work.

Impurities in chemicals are also common and certain impurities are harmless if present only to a limited degree. Other impurities are very harmful if present in any degree and such impurities should not exist in photographic chemicals.

Another thing to be considered is the combination of chemicals. Our formulae are printed in proper order. The chemicals should be dissolved in the order given to secure a perfect combination.

Still another thing equally important in the combination of chemicals is care in selection of all chemicals used to make up a given formula. For example, Eastman Permanent Crystal Pyro is perfect, but its good qualities are partially destroyed if combined with sodas of indifferent quality. Eastman Sodas are perfect, but when combined with inferior developing agents cannot of course make up for the shortcomings of the low grade developing agents, and so on through the list. Every chemical used alone should be the best that can be produced and every chemical used in combination with other chemicals should be of high grade quality, as otherwise the entire combination is affected and possibly destroyed.

M. W. Tyree, Raleigh, N. C. Sec, P. A. of A.

M. W. Tyree, Raleigh, N. C. Sec, P. A. of A.

From an Artura Iris Print.

Chemicals marked C-K tested must be of proper quality before they receive that mark. They are packed in a way to preserve that quality until used.

The photographer who uses C-K tested chemicals is not experimenting with the unknown - is not running the risk of spoiling good plates and paper with poor chemicals or chemical combinations. That's why we test and pack chemicals under the named C-K tested.

Our plates and paper to be successful must produce results and even our extreme care in making good, reliable sensitized materials may be entirely offset by the use of unreliable chemicals.

Your dealer carries a full line of C-K tested chemicals - a line that comprises all chemicals in which purity and proper strength are essential.

Specify C-K tested when you order and when you receive the goods look for this seal on the label:

The Time: Jan. 17, 18, 19

The Place: Toronto

The Event: Eastman School of Professional Photography and again The Time: Jan. 24, 25, 26

The Place: Montreal

The Event: Eastman School of Professional Photography.

L. A. Dozer, Bucyrus, Ohio Treas., P. A. of A.

L. A. Dozer, Bucyrus, Ohio Treas., P. A. of A.

From an Artura Iris Print.