Chemical Recorder

A form of telegraphic recorder in which the characters, often of the Morse alphabet or some similar one, are inscribed on chemically prepared paper by decomposition affecting the compound with which the paper is charged. In the original chemical recorder of Bain, the instrument was somewhat similar to the Morse recorder, except that the motionle stylus, S, always pre ing against the paper was incapable of making any mark, but being of iron, and the paper strip being impregnated with pota ium ferrocyanide, on the pa age of a current a stain of Pru ian blue was produced where the stylus touched the paper. The current pa es from the line by way of the iron stylus, through the paper, and by way of a bra surface, M, against which the paper is held and is pre ed by the stylus, to the earth. This recorder is extremely simple and has no part to be moved by the current. The solution in which the paper is dipped contains a mixture of pota ium ferrocyanide and ammonium nitrate. The object of the latter is to keep the paper moist. In recent recorders a solution of pota ium iodide has been used, which gives a brown stain of free iodine, when the current pa es. This stain disappears in a few days. IMG:8956969607833025625_117F83.jpg: Fig. 83. BAIN'S TELEGRAPH EMPLOYING CHEMICAL RECORDER. In the cut, R is the roll of paper, B is a tank of solution with roll, W1, for moistening the paper; M is the bra surface against which the stylus, S, pre es the paper, P P; W, W are feed rollers; T is the transmitting key, and zk the battery; Pl, Pl are earth plates. The apparatus is shown duplicated for each end. 118   STANDARD ELECTRICAL DICTIONARY.