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

by Joseph W. Lovibond

Detection of Forgeries.—The system and apparatus is used by Professor A. S. Osborne, Examiner of Questioned Documents, New York City, for determining the variety of ink, the age of the writing, and the detection of forgeries. A full description of the process will be found in his work entitled Questioned Documents, published by the Lawyers’ Co-operative Society, Rochester, N.Y.

PLATE IX
SIX ANILINE DYES.
CURVES ILLUSTRATING THE RATE OF FADING BY EXPOSURE TO LIGHT.

To face page 78.[Lovibond, Colour Theories.

The application to chemical analysis is too well known to require enlargement here.

Fig. 9.

Dyes.—As an example of the use of the system in the valuation of dyes, [Fig. 9] illustrates the specific colour curves of four samples of Methylene Blue. No. 1 was priced at 5s. 9d. and No. 2 at 5s. per lb., Nos. 3 and 4 were not priced, the solutions were measured in percentages from 0·001 to 0·048 in distilled water. To find the cost per unit of colour in the priced samples is only a question of simple arithmetic, which furnishes data for the valuation of the unpriced samples.