Army manual of hygiene and sanitation, 1934 / [War Office].

Date:
1941
Catalogue details

Licence: Public Domain Mark

Credit: Army manual of hygiene and sanitation, 1934 / [War Office]. Source: Wellcome Collection.

    41/310 (page 43)
    the purification of small quantities of water, especially where cholera is prevalent. The best method is by the use of acid ~ sodium sulphate, which forms sulphuric acid. It is issued in fifteen grain tablets and one tablet is added to every pint of water. Chlorine is the chemical most used for water purification. At ordinary temperatures it is a gas which is very poisonous and rapidly kills all living matter. In very dilute solutions chlorine is not however harmful to man. It dissolves easily in water to form hypochlorite solution, which is also poisonous, and it is. contained in several solid substances which readily _ give off their chlorine when added to water. Organic matter _ or dirt in water absorbs chlorine and lessens its action on germs _and for this reason the water should be clarified first; it also has the disadvantage of giving the water a disagreeable smell and taste; these, however, pass off or can be removed. -Chlorine, therefore, can be used as a gas, or in liquids or solids from which it is set free. In the solid form it is avail- able as bleaching powder, chlorosene and many other similar substances. Water sterilizing powder used in the regimental water cart consists of a mixture of four parts of bleaching _ powder and one part of quicklime and is supplied in four-ounce _ tins with a scoop capable of holding thirty grains of the powder ; . this powder should contain not less than 25 per cent. of chlorine and the amount to be used is determined by means of the Horrocks’ test (see Appendix 4). ~ Chlorosene (super-tropical bleach, 30% available eniganey is also used in the chlorine and chloramine treatment of water. It is more stable than bleaching powder and therefore more suitable for use in the tropics. _ Automatic chlorinators may be used for bulk purification of water and the dosage of chlorine regulated by means of a | _chloroscope. _ Ammonia chlorine process (chloramine).—Mixtures of am- -monia and chlorine have properties differing from chlorine and _the compounds produced are known as chloramines. Chlora- mine is a more powerful purifying agent than chlorine alone and, a matter of very great importance, it leaves a tasteless and safe water when properly used. _ Chlovamine possesses the further advantage over chlorine of not being deviated by organic matter, but, owing to its -Telatively slow powers of penetration, water should be clarified as well as chloraminated. — The dose of chloramine recommended to purify water in one hour is between one and two parts per million. _ This method of purification, originally devised by Harold at the Army School of Hygiene, is used in the Elliott mobile — 2*—(2187) 43 Fl ~ ae