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Article XII.
From the Annales de Chimie et de Physique, vol. lvii. p. 225.
AMONG the remarkable properties which chlorine possesses, there is one which became advantageous to manufactures very shortly after its discovery, viz. its energetic action on colouring matter. The illustrious Swede to whom we owe the knowledge of this body, mentioned the facility with which it destroys vegetable colours; but that which to Scheele was merely an interesting experiment, became to Berthollet the basis of a new art. Berthollet conceived the happy idea of applying the decolorizing property of chlorine to the purpose of bleaching, and the success which he obtained even in his first attempts exceeded his hopes. Up to this period, cotton and linen manufactures were spread in meadows, and by exposing them alternately moist and dry to heat and cold, light and shade, they were indeed, after a very long time, perfectly bleached.
The eagerness with which a new process was welcomed will be conceived, when manufacturers could produce by it in a few hours what previously occupied several months. The new process of bleaching, to which public gratitude gave the name of the Berthollean method, was generally adopted, and chlorine thus proceeded from the laboratory of the chemist to the workshop of the arts. Manufactures were first bleached with chlorine gas, and afterwards with the aqueous solution; but it was soon found that its penetrating smell, and its powerful action on the lungs, were very prejudicial to the workmen employed. In his endeavours to free them from these dangerous exhalations, Berthollet perceived that by the addition of a little quicklime, and even carbonate of lime or of magnesia, the penetrating smell of the chlorine was removed from the aqueous solution, without diminishing its bleaching power. This important observation conducted him to another still more important. He stated that if, instead of dissolving the alkali in aqueous solution of chlorine, a current of the gas was made to pass into the alkaline solution, it would dissolve a much larger quantity than mere water, and the liquid possessed decolorizing power in a much higher degree.
These new compounds, in which the chlorine seemed in some degree
