Light and Colour Theories, and their relation to light and colour standardization

by Joseph W. Lovibond

In general use by the following Industries—

Brewing and Malting.
Tanning.
Wine and Spirit Merchants.
Dyeing and Printing.
Paint, Oil and Varnish Merchants.
Millers.
Water Works Chemists.
Ceramic Works.
For estimating per cent. of Carbon in Steel.
For estimating per cent. of Ammonia.
For estimating Colours for Anthropological Classifications.
For estimating Smoke Densities.
For estimating Haemoglobin in the Blood.
For estimating Colour of Whale Oil, etc., etc.

THE METHOD.

The colour composition of any object may be measured by superimposing units of different colours until the colour of the object is matched. A convenient apparatus is furnished for this purpose. The composition of the colour is learned by merely reading the markings on the glasses.

It is of course necessary that in the isolation of colour rays, some unit for measuring the intensity of both light and colour be established. As will be explained later, all such units are necessarily arbitrary. In this method the unit has been established by taking the smallest amount of colour easily perceptible to the ordinary vision. This unit or “one” is divided into tenths in the darker shades, and hundredths in the lighter scale. One one-hundredth is the smallest amount of colour measurable by a normal trained vision.

When equivalent units in the three colours are superimposed, their equivalent value (not their aggregate value) represents so much white light absorbed. For instance, 2 R. + 2 Y. + 2 B. absorbs two units of white light.

When the absorptive power of the colour standards is less than the intensity of the light, associated white light remains.

JOSEPH W. LOVIBOND.

The Colour Laboratories,
Salisbury.
December, 1914.