[1] Nesfield. Public Health, 1903, =15=, 601. [2] Darnall. J. Amer. Pub. Health Assoc., 1911, =1=, 713. [3] Kienle. Proc. Amer. Waterworks Assoc., 1913, 274. [4] West. J. Amer. Waterworks Assoc., 1914, =1=, 400-446. [5] Jackson. Proc. Amer. Waterworks Assoc., 1913. [6] Hale. Proc. N. J. San. Assoc., 1914. [7] Pettenkofer and Lehmann. Munich Acad., 1887. [8] Marshall. Conv. Amer. Elect. Chem. Soc., 1917. Eng. and Contr., 1918, =49=, 40. [9] Faraday. Q. J. S., =15=, 71. [10] Roozeboom. Rec. Trav. Chim., 1885, =3=, 59. [11] Forcrand. Comp. rend., 1902, =134=, 991. [12] Pedler. J. C. S., 1890, =83=, 613. CHAPTER VIII ELECTROLYTIC HYPOCHLORITES AND CHLORINE Since 1889 when Webster first proposed the use of electrolysed sea-water as a disinfectant, various attempts have been made to introduce electrolytic hypochlorites for the bactericidal treatment of water and sewage. Two of these preparations were named Hermite fluid, and electrozone (c.f. page 5). Sodium hypochlorite, made by passing chlorine into solutions of caustic soda, or by the decomposition of bleach by sodium carbonate, has also been used and preparations of this character have been sold under such names as Eau de Javelle, Labarraque solution, chloros, and chlorozone. These solutions contain mixtures of sodium hypochlorite and sodium chloride together with some free alkali. Chlorozone was the name given by Count Dienheim-Brochoki to a number of preparations patented in 1876 and subsequently down to 1885. They were produced by passing air and chlorine into solutions of caustic soda. Lunge and Landolt[1] have shown that the air introduced is without effect and that the advantages claimed for chlorozone are illusory. The earliest electrolytic installation on this continent was operated at Brewster, N. Y., in 1893 and since that date several plants have been erected where local conditions conduced to economical operation. When a uni-directional current of electricity is passed through a solution of sodium chloride, the salt is dissociated and the components liberated, NaCl = Na + Cl. If the elements are not separated, the chlorine combines with the sodium hydrate, formed by the action of the sodium on the water, to form sodium hypochlorite. The equations 2Na + 2H_{2}O = 2NaOH + H_{2}, and 2NaOH + Cl_{2} = NaOCl + NaCl + H_{2}O show that only one-half of the chlorine produced is found as hypochlorite; the other half reforming sodium chloride. Several types of electrolysers have been used for the production of hypochlorites and chlorine but only two are suitable for water-works purposes: in one, the cathodic and anodic products recombine in the main body of the electrolyte; in the other, the diaphragm process, they are separated as removed and the final products are chlorine gas and a solution containing caustic soda and some undecomposed salt.