to colourless earths, especially to alum: but the dyer has especially to do with animal and vegetable products as the ground of his operations.
586.
Everything living tends to colour—to local, specific colour, to effect, to opacity—pervading the minutest atoms. Everything in which life is extinct approximates to white (494), to the abstract, the general state, to clearness47, to transparence.
587.
How this is put in practice in technical operations remains to be adverted to in the chapter on the privation of colour. With regard to the communication of colour, we have especially to bear in mind that animals and vegetables, in a living state, produce colours, and hence their substances, if deprived of colours, can the more readily re-assume them.
XLVII.
COMMUNICATION, APPARENT.
588.
The communication of colours, real