228 KEVIF.W — TROPTCAF, MEDICINE, ETC. 



Water— chlorine, bromine or ozone. In water containing in excess salt or organic matter, a strength 

 roniiiiiied of 1 in 200,000 is advisable. The addition of Tachyol in a strength of 1 in 500,000 

 causes a transient turbidity in water, which entirely disappears in 24 hours. 



Various methods of purifying water are in use, but mention may be made of precipi- 

 tation, boiling and filtration. 



Of precipitation methods, tannin and the juices of various vegetables have been employed, 

 but the agents most commonly used are alum and lime. Alum, in a strength of 6 grains to 

 the gallon, is an excellent clarifier of muddy water. It has also a bactericidal effect on 

 many water bacteria. The addition of 5 grains of lime further enhances the clarifying 

 effect of these agents. Unfortunately, alum has no bactericidal action on such pathogenic 

 organisms as the typhoid bacillus or cholera vibrio. 



Boiling as a method of purifying water is excellent, as all organisms are destroyed, and 

 further the amount of hardness in the water is reduced. The main disadvantage of this 

 method of purification is the fact that the water takes some time to cool sufficiently 

 for potable purposes, and, owing to the air being drawn off, the boiled water has rather an 

 insipid taste. To overcome this difficulty, various water sterilisers have been in the market 

 and of some of these mention may be made. 



The Lawrence Patent Water Softener and Steriliser is one in which a special system of 

 boiling is employed, whereby the free carbonic acid, which holds in solution the carbonates of 

 lime and magnesia, is driven off and consequently these carbonates are removed from the 

 water and are deposited in a solid form. The boiling is effected continuously, the water as 

 it is passed through the apparatus being heated progressively until it reaches a state of 

 violent ebullition. It is then rapidly cooled and leaves the apparatus only slightly warmer 

 than when it entered it. The smaller plants can deal with from 100 to 3000 gallons per 

 hour, while there are large town supply plants treating 50,000 gallons per hour. 



The features which are said to distinguish this system are : — 



1. Low first cost and low working expenses. 



2. Absolute efficiency and rapidity of action. 



3. No chemicals are used, except occasionally a little carbonate of soda, i.e. when it is 

 desired to get rid of permanent hardness. Great simplicity and ease of working, no 

 complicated parts, and nothing to get out of order. 



4. The utmost ease of cleaning, only one-half the deposit of a lime process, and that in 

 a solid form. 



A small apparatus of this type has been recommended for use at the Fort, Khartoum, 

 where the well water is both hard and impure, and where difficulties as regards transport, 

 etc., prevent the river supply being utilised. 



There are also the Forbes^ Water Steriliser and the Naiche- Automatic Water Steriliser 

 on the market. Both of these sterilisers claim the advantage that the air of the water is 

 retained in solution. 



The Ford-Palliser^ Drinking Tank is another form of steriliser placed on a cart and 

 intended for use in the army. The advantage of this drinking tank is that 50 gallons of 

 water can be boiled in an hour, while the cart is in motion ; the tank is kept level 

 by means of a gimballed arrangement and the water is cooled by a tank containing saltpetre. 

 Faichnie* calls attention to an important point in connection with water supply for troops 

 in camp and on the march, viz., the great importance of a pure water supply for 

 cleansing vessels used for eating and drinking. If boiling water be not available for washing 

 up plates and knives and drinking vessels these may all become infected by the use of unsafe 

 water, and the virus may remain active for days. Methods of water analysis always 

 require time and are quite impracticable in camp and on the line of march, but the 

 difficulty of supplying pure water to the troops is now more or less surmounted by the use 

 of the new pattern of army cart, which is fitted with sponges to stop sediment and with 

 candles to stop microbes, and can supply 210 gallons of water per hour. Where there is 

 difficulty in using carriage transport, as in mountain warfare, mule filters are found to be 

 very serviceable. 



' Simpison, W. J. (June Ist, 1903), " Water Supplies." Journal of Tropical Medicine, p. 172. 

 " Simpson, W. J. (Juue 15th, 1903), "Water Supplies." Journal of Tropical Medicine, p. 192. 

 ^ Ford-Palliser Drinking Tank. Lancet, June, 1904. 



♦ Faichnie, N. (August 31st, 1907), " Water Supply in the Camp, on the March, in Battle." British Malical 

 Journal. 



