286 EXPERIMENT STATION RECORD. 



actions rapidly change. A very sensitive peptone culture medium yielding uni- 

 form results and large gas volumes consists of peptone 3 to 4 per cent, lactose 

 0.8 per cent, potassium chlorid 0.6 per cent, reaction + 1 per cent. Such media 

 show little change on keeping." 



Studies on the culture media employed for the bacteriological examination 

 of water, III, E. M. Chamot, C. M. Sherwood, and R. C. Lowary (Jour. 

 Amer. Chem. Soc, 37 (1915), No. 9, pp. 2198-2204, figs. 2).— In the third paper 

 of this series studies were made to determine the composition of the gases 

 formed in the fermentation of the lactose-peptone media noted in the above 

 paper. 



It was found that " the percentage of carbon dioxid present in these gases in- 

 creases with an increase in peptone, meat, or liver until an equivalent of ap- 

 proximately 4 per cent peptone is reached, after which it remains substantially 

 constant. Hydrogen decreases with a rise in peptone until 4 to 5 per cent of 

 peptone is reached, after which the percentage of this gas remains substantially 

 constant. The ' gas ratio ' varies with the concentration of the nitrogenous 

 material present in the medium. No methane appears to be formed unless oxy- 

 gen (air) has free access to the media and the inoculated medium stands for 

 over 24 hours. A small but nearly constant amount of nitrogen Is found in 

 the gases of fermentation. An excess of oxygen retai-ds gas formation and 

 tends to increase the percentage of carbon dioxid." 



The sterilization of water with lime, C. Haller (Stddtisch. Tiefbaw., 4, 

 l)p. 299-303; nhs. in Clicm. ZcnIhL, 191.',, I, Xo. 2, p. 193; Chem. .\bs.. S (19l!f), 

 No. 12, p. 2206). — The disinfection of water wIumi calcium oxid in sufficient 

 quantity to combme with the free and half-bound carbon dioxid and magnesium 

 is added is said to be not due to the toxic effect of calcium oxid. Bacteria of 

 the typhoid and coli groups die in 48 hours owing to the fact that intestinal 

 bacteria can not live in water from which the free and half-bound carbon 

 dioxid have been removed. Water which has been treated with calcium oxid 

 is said to be soon safe for use even if it had been previously polluted with 

 Bacilhis typhosus or sewage. 



Farm water supplies (Minncapoli.t, Minn.: Bd. Ileal th, 1915, pp. 29, figs. 

 15). — This paper deals mainly with the sanitary side of farm water supplies. 

 It points out in a comprehensive manner the dangers lying in a polluted water 

 supply and describes and illustrates bad well, spring, and cistern conditions 

 and remedies for the same. 



It is pointed out that in the movement of water through the soil natural 

 purification takes place. " If a suflicient layer of soil exists between the sur- 

 face and the supply, complete purification will occur. The amount of inter- 

 A-ening soil necessary for this purpose depends upon the nature of its composi- 

 tion. Under ordinai'y conditions, as found to exist in Minnesota, 10 vertical 

 feet of soil will be sufficient, provided the well itself is properly locate<l and 

 constructed. It is a common belief that pollution may seep through the soil 

 for long distances and gain entrance into the well in this way, but such an 

 idea is not universally true. :ind. as a matter of fact, the danger of surface 

 wash getting into a well in this manner is very slight, and in most localities 

 in Minnesota can be ignored as a source of danger." 



Special attention is also drawn to the dangers of priming wells ami in the 

 use of deep-dug wells for the deposition of sewage. 



Clean water and how to get it on the farm, II. W. Trxtllinger (Xat. Food 

 Mag., 39 (1915), Xo. 3, pp. 193-200, figs. 8).— The substance of this article has 

 been noted from another source (E. S. II., 33, p. 289). 



Water supply, plumbing, and sewage disposal for country homes, R. W. 

 Teullinger (Dom. Engin. [Chicago Ed.], 72 (1915), Nos. 7, pp. 19^-197, figs. 



