That which possesses the power of acting or producing effects upon anything else. Pyro is a developing agent; Hypo is a fixing agent, etc.


Particles or bubbles of air between surface of plate, or paper, and solution. Caused by air in the water, or by splashing solution onto plate or paper instead of pouring it on with a quick, even sweep.


An instrument used by artists for finishing enlargements, and for working up various kinds of prints. Compressed air is employed to force a fine spray of ink or color onto the print.


An organic substance found principally in the white of an egg. Quickly decomposes. Ammonia is employed as a preservative. Used in sensitizing paper, to which it gives a peculiar and characteristic gloss.

Albumenized Paper

(See Paper, Albumenized.)


The process of coating either plates or papers with a solution of albumen.



Ethyl Alcohol, or Spirits of Wine.

Colorless, volatile, inflammable liquid; burning taste. Its uses are many. Used as a solvent for pyroxyline in the collodion process. Used in the developing solution to make it flow more evenly. Many varnishes are compounded with it. As it takes up water readily it is used for rapidly drying plates, papers, etc. Absolute alcohol, which is 100% pure, is practically unavailable for photographic use. 95% alcohol, also known as rectified spirit, is the best to employ.

Test For Purity

To test its purity the 95% alcohol should burn with a perfectly blue flame. If water is present to any degree, even if it were 93% pure, the edges of the flame will be a trifle red, and the more water present in the alcohol the redder will be the flame.


Methylated Spirits.

Strong alcohol, to which has been added 10% of wood alcohol.

Methylic Alcohol

CH4O - X. Wood Alcohol, or Naphtha. Prepared by the dry distillation of wood. Used as a solvent for various colors, which dissolve better in it than in ordinary alcohol. Used on a tuft of cotton to reduce images or fogged portions of negatives. Applied with cotton to white parts of gaslight prints it will remove black streaks or lines (abrasion marks) and mealy effects.

Wood Alcohol

(See Alcohol, Methylic.)


The direct opposite of an acid. A term often applied to an accelerator. Turns red litmus paper blue. Alkalies have the power of neutralizing acids. Strong solution of alkalies should be handled with care as they act powerfully on the skin.

Equivalent Quantities of Alkalies

For practical purposes the equivalent proportions of different alkalies are as follows:

Potassium Carbonate.............................

165 parts

Sodium Carbonate (crystals).................

268 parts

Caustic Soda..........................................

80 parts

Caustic Potash........................................

112 parts

So far as the acetates, carbonates and phosphates of either potassium or sodium are concerned, there is but little or no difference in their action in the toning bath.