Page:TheAmericanCarbonManual.djvu/19



in the strict sense of the word, is an image in carbon produced by the action of light. The term, as commonly used by photographers, has, however, a wider application, and is employed to designate any sun picture produced in permanent pigments, whether consisting of carbon or not.

Almost all the methods which have been proposed for the production of such pictures depend upon one principle. They are based on the fact that light renders certain soluble bodies insoluble in the usual menstrua. This principle admits of varied application in producing pictures; but in the processes which have been brought to the highest practical perfection, some coloring matter—Indian ink or lampblack for instance—has been added to a colorless body like gelatine or gum, which,