In 1859 James Watt discovered that hypochlorites were produced by the electrolysis of the chlorides of alkalies and alkaline earths.
Joseph Race, in his 'Chlorination of Water,' p. 106, maintains that in the electrolysis 'of the solution of sodium chloride, the chlorine may combine with the sodium hydrate formed by the action of the sodium on the water to form sodium hypochlorite, of the chlorine produced is found as hypochlorite and the other half reforming sodium chloride. . The electrolytic hypochlorite method offers sonic advantages, but in the great majority of plants it cannot economically compete with bleach." Commercial bleaching powder is formed by passing chlorine gas over slacked lime. It is also known as calcium hypochlorite and as stated by Joseph W. Ellms in his 'Water Purification.' p. 369. consists of several chemi cals formed by the reaction of chlorine and calcium, such as calcium oxychloride, calcium chloride, calcium chlorate, calcium hydroxide, calcium carbonate, calcium sulphate, oxides of Na K Mg. Fe and Si. and moisture. These un dergo reactions resulting in the evolution of oxygen which is set free and is destructive of micro-organisms. Oxygen is the potential en ergy that destroys them.
Calcium hypochlorite was first used effec tively in this country to purify the waters of the Benton reservoir at Jersey City of bac teria. Since that it has been and is still ex tensively used as a disinfectant Its germicidal tnero' is said to equal ozone as an oxydiring and steriliring agent, and is much cheaper than ozone.
Hypochlorite of sodium, obtained by the salt, has some advantages over ete of calcium, which produces sludge, dogs orifices and is dangerous to fish, when dumped into running waters.
Joseph Race, in his (alorination of Water,' p 17, says that son dissolving bleach in water the first action is the decomposition of calcium oxychloride into an equal number of molecules of etch® b3rpochlorite and calcium chloride.' At pece 20 he says: •The addition of small quantities of sodium chloride (0.1 per cent) in creases the hydrolysis of bleach solutions but mock larger quantities tend to the opposite di rection . . . . Sodium chloride in the absence of hypochlorites was found to have no influ ence upon the viability of B. coli in water.°
Bleaching powder is one of the most effi cient germicidal agents. The neutralizing chem ical for an overdose of bleaching solution is sodium thiosulphate at one-half the amount of the former.
F. Raschig, Samuel Rides' and Joseph Race have developed the new germicide, known as dtkramine (NH,CI), formed by adding am moons to bleaching solution, which increases the germicidal action of the latter. Joseph Race has stated that from numerous experiments he conclude at the mos. -non of the come and was two pan, l,) \‘,. of chlo rine to of e part by weight of ammonia. Consult Race. J., •-• ' — H - • , \.‘ ' ., , ' ? p 118).
On a recent inspection oz inc operation of the chloramine process at Ottawa, the author learned that the after-growth noted after the use of hypochlorite in same plants amounting to 20, 000 bacteria per cubic centimeter has been elimi nated and that the B. coli commas.: had been measly all destroyed. Race reported that similar results followed the application of chloramine at the*tol Hill reservoir in Denver, where bacteria d from 15,000 to 10 per cubic centimeter. t re is important to the health of a community that some process be adopted that will eliminate or destroy pathogenic bacteria, so that less than 100 bacteria per cubic centi meter survive whatever process of purification that community may adopt. Otherwise, its water supply is not of that degree of purity which hygienic standards require for potable uses. Such standards have been greatly raised in the last half century, and no enlightened community would be suffered to use such water supplies at • ,• general use before the nature and of the rn. • Isms in so waters were and par tially understood. Therefore the modern proc esses for the purification must be efficient, and to be so they must conform to scientific stand ards. Communities will not be permitted longer to provide water laden with pathogenic mi crobes, and if any one of the foregoing processes of purification fail to eliminate or destroy such then it ought to be superseded by of a more efficient process, as was done at Ottawa by the substitution of the diloransine in place of liquid chlorine.