  The purpose of this work is to demonstrate that colour is a determinable property of matter, and to make generally known methods of colour analysis and synthesis which have proved of great practical value in establishing standards of purity in some industries. The purpose is also to show that the methods are thoroughly scientific in theory and practice, and that the results are not likely to be changed by further discoveries. Also that out of the work done a new law has been developed, which the writer calls the Law of Specific Colour Development, meaning that every substance has its own rate of colour development for regularly increasing thicknesses. THE THEORY.Of the six colours in white light—red, orange, yellow, green, blue and violet; Red, Yellow and Blue are regarded as dominants, because they visually hold the associated colours orange, green and violet in subjection. An equivalent unit of pure red, pure yellow and pure blue is adopted, and incorporated into glass. The unit is multiplied to obtain greater intensities, and divided to obtain lesser intensities. The coloured glasses are called absorbents. The red absorbent transmits violet, red and orange, but the red ray alone is visible as colour, until the other absorbents are superimposed, and the character of the group of rays changed. In the same way yellow transmits orange and green, and blue transmits green and violet, whilst the yellow and blue alone are visible as colour. Orange, green and violet are here called subordinates, which may be developed as follows:— Or. = R. + Y.Gr. = Y. + B. Vi. = B. + R. Twenty-five years’ experience in the application of the theory and the method to the requirements of practical work, have given no reason for change. Following will be found a list of awards from International Juries and Scientific Societies, also a list of industries in which the writer’s method is giving entire satisfaction.
Awards by Scientific Societies. Sanitary Institute of Great Britain— Royal Sanitary Institute— International Congress on School Hygiene— Royal Sanitary Institute— Smoke Abatement Society, Sheffield— Royal Sanitary Institute— Franco-British Exhibition— International Medical Congress— Royal Sanitary Institute— Royal Sanitary Institute— Formal Adoption of Tintometer Standards by— The Petroleum Industry. In general use by the following Industries— Brewing and Malting. 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, | ||||||||
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