1917] RURAL ENGINEERING. 787 



gines were visited and the conclusion reached, after the information obtained 

 was examined, was that in the majority of cases the plants now pumping by 

 gas engines could not be taken over for electric service to the advantage of 

 either the consumer or the company. There are certain classes of power irriga- 

 tion for which the gas engine, due to its low annual cost, if operated but little, 

 may be used with considerable economy as compared with electric power." 



The use of cement on national irrigation works, A. P. Davis {Proc. Nat, 

 Assoc. Cement Users, 9 {1913), pp. 258-265, figs. 7).— This is a statement of the 

 use made by the U. S. Reclamation Service of cement in irrigation structures. 



" Since its organization the Reclamation Service has used about 1,500,000 bbls. 

 of Portland cement, representing about as many cubic yards of concrete. It has 

 built about 7,000 miles of canals, 69 tunnels aggregating 111,000 ft., has built 

 18 storage dams and 25 diversion dams, about 2,000 concrete structures upon 

 canals, and about 32,000 wooden structures. It has built altogether 2,908 

 bridges with an aggregate length of about 62,000 ft. It has built 436 offices 

 and dwellings and about as many other buildings used for barns and store- 

 houses." 



Improvements proposed in the javellization of potable water for field 

 service, Comte (Jour. Phurm. et Chim., 7. ser., 14 (1916), No. 9, pp. 261-26S; 

 abs. in Chem. Abs., 11 (1911), No. 6, p. 678). — A summary of service experience 

 leads to the recommendation that a solution of 20 gra. of powdered potassium 

 permanganate in 1 liter of hot water and 20 gm. of concentrated sulphuric acid 

 be used for cleaning and deodorizing containing vessels. 



It has been found that a uniform method of javellization is not applicable, 

 owing to the variation in the organic impurities in the water and variations m 

 the Javelle solution. It is pointed out that a definite amount of a given Javelle 

 solution corresponds to a given water. This ratio is determined rapidly by 

 placing 100 cc. of the water to be examined into each of five vessels and adding, 

 respectively, 1, 2, 3, 4, and 5 drops of a 1 : 100 strength Javelle solution. After 

 stirring and a wait of 20 minutes about 1 cc. of a potassium iodid starch re- 

 agent is added and again stirred. Several samples will then be blue. The 

 sample of lowest concentration giving a blue color indicates the number of 

 drops of undiluted Javelle solution necessary for the treatment of 10 liters of 

 the water with the same dropping instrument. The starch reagent contains 

 1 gm. each of starch, potassium iodid, and crystalline sodium carbonate. 



Experiments upon the purification of sewage and water at the Lawrence 

 Experiment Station during the year 1915 (Ann. Rpt. Dept. Health Mass., 1 

 (1915), pp. 577-429, figs. 4). — This section of the report gives in detail the re- 

 sults of the water and sewage purification experiments at the station for the 

 year 1915. 



Annual report of the Baltimore County [Md.] roads eng^eer for the year 

 ending December 31, 1916, W. G. Suceo (Ann. Rpt. Roads Engin. Baltimore 

 Co. [Jfd.], 1916, pp. 81, pi. 1, figs. i7).— This is a report of work and expendi- 

 tures on road construction, maintenance, and repair in Baltimore CJounty, Md., 

 for 1916. 



Influence of grading on the value of fine aggregate used in Portland 

 cement concrete road construction, F. H. Jackson, jb. (U. S. Dept. Agr., Jour. 

 Agr. Research, 10 (1911), No. 5, pp. 263-214, figs. 10). — Experiments showing in 

 a general way the effects of variations in the grading of fine aggregate on the 

 resistance to wear of road concrete are reported. 



It was found " that but few naturally occurring concrete sands are as coarse 

 as those making the strongest mortars, according to these tests. Neither has 

 the fact been overlooked that the best mortar, when combined with stone or 

 24656°— 18— No. 8 1 



