Test for Oxalates

(See Oxalates, Test for.)

Test for Potassium Salts

(See Potassium Salts, Test for.)

Test for Silver Salts

(See Silver Salts, Test for.)

Test for Presence of Hypo

(See Sodium Hyposulphite, Test for Presence of.)

Test for Sulphites

(See Sulphite, Test for.)

Test Paper

(See Paper, Test.)

Test Tube

A thin glass tube having a rounded bottom. Used for making chemical tests.

Water Test

(See Water Test.)

Testing Lenses

(See Lens Tests.)

Centigrade Thermometer

A thermometer used in Europe, but little in America. A space between freezing and boiling point is divided into one hundred parts, the former being marked at zero, while the latter point is one hundred degrees. To convert Centigrade to Fahrenheit (the latter being used in America) it is necessary to multiply by 9, divide by 5, and add 32.

Fahrenheit Thermometer

The standard measure of temperature in the United States. The freezing point is 32 degrees. The boiling point of water 212 degrees, which leaves 180 degrees between these two points. In the Centigrade thermometer (See Thermometer, Centigrade) this space is divided into 100 degrees. To reduce Fahrenheit degrees to Centigrade, subtract 32, multiply by 5, and divide by 9.

Reaumur Thermometer

A thermometer scale in which the freezing point is marked o° and the boiling point 8o°. To reduce Reaumur degrees to Fahrenheit, multiply by 9, divide by 4, and add 32. To reduce Reaumur degrees to Centigrade, multiply by 5 and divide by 4.

Thiosulphate of Sodium

(See Sodium, Hyposulphite.)

Three-Color Carbon Process - VIII.

Three-Color Gum Process - VIII.

Three-Color Photography - VI; VIII

(See Color Photography.)

Tilting Tripod Head

(See Tripod Head, Tilting.)

Time Development

(See Factorial Development.)

Time Exposure

An exposure which is not instantaneous.

Tonal Values

The different degrees of light and shade in a picture. When the various colors in the subject have been truthfully rendered in monochrome in the photograph, and the effect of distance and atmosphere is natural, the photograph is said to have correct tonal values.

Tone

The surface color of a finished print.

Toning Bath

A solution employed to change the color of a print by depositing a thin coating of gold or platinum over the image. There are various kinds of toning baths for different kinds of paper.

Combined Toning Bath

A bath for toning prints, in which the toning and fixing solutions are combined.

Transfer Paper

(See Temporary Support.)

Translucent

A substance is translucent when it allows the rays of light to pass through it, yet the substance is sufficiently opaque so that objects are not visible through it.