1918.] EUEAL ENGINEEKING. 691 



A chapter on the chemical character of some surface waters of Alaska, by 

 R. B. Dole and A. A. Chambers, is included. 



" The few analyses available show a favorable condition of the surface 

 waters. They indicate that the streams in general yield supplies moderate in 

 mineral content, low in clilorid and sulphate, and essentially calcium carbonate 

 in character. All the supplies tested are low enough in mineral matter to be 

 useful for domestic and industrial use, and they resemble in composition the 

 least mineralized waters of the United States." 



"Well waters from farm homesteads, F. T. Shutt {Canada Expt. Farms 

 Rpts. 1916, pp. 180-185). — Analyses of 173 samples of Canada farm water sup- 

 plies reported show that 22 per cent were pure and wholesome, 24 suspicious 

 and probably dangerous, 32 seriously polluted, and 22 per cent too saline to be 

 potable. 



Removing' the taste due to alg-ae in drinking' water, A. C. Houston (Brit. 

 Med. Jour., 2919 {1916), pp. 816, 817; Pluirm. Jour. [London^, 4. ser., 98 {1911), 

 p. 139; abs. in Jour. Sac. Chem. Indus., 36 {1917), No. 4, p. 232). — "Potassium 

 permanganate, added in quantities of 2.5 to 5 lbs. per milliwn gallons, proved 

 much more effective than hypochlorites in removing the nauseous taint due to 

 the growth of alga? in reservoirs. . . . The use of hypochlorites involves the 

 risk of merely replacing one taste by another or even of introducing a super- 

 added taste." 



The activated sludge process of sewage treatment: A bibliography of the 

 subject, J. E. Porter {Rochester, N. Y.: General Filtration Co., Inc., 1917, pp. 

 JfO). — This is a bibliography of the subject with brief abstracts, patents, news 

 items, etc., compiled from current literature. 



A preliminary report on blended Portland cement, E. S. McCandliss {Bv.1. 

 School Mines and MetaUurg., Univ. Missouri, tech. ser., 3 {1917), No. 3, pp. 

 53-\-13, figs. 22). — Experiments are reported from which the conclusions are 

 drawn that " Portland cements of a fineness sufficient to pass a No. 200 sieve 

 may be blended as much as 40 per cent, by weight, with quartz sand, the latter 

 of a fineness sufficient to pass a No. 65 sieve, but not fine enough to permit of 

 more than 20 per cent to pass a No. 200 sieve, and the resulting blended cement 

 will satisfactorily pass the requirements of the present standard specifications 

 for Portland cement of the American Society for Testing Materials. Quartz 

 sand is a satisfactory substitute for the inert clinker particles in Portland 

 cement in maintaining the present physical characteristics of the latter, when 

 used in amounts not to exceed 30 per cent, by weight." 



The effect of sulphid on cement, J. C. Witt {Philippine Jour. Sci., Sect. A, 

 11 {1916), No. 6, pp. 273-290, pi. 1, fig. i ) .—Experiments on the influence of a 

 sulphid solution on the properties of cement are reported. 



It was found that the time of setting is greatly modified by the presence of 

 sodium sulphid, being retarded by the low concentrations, but after reaching a 

 maximum further additions accelerate the set. In general, the cements highest 

 in iron were the most sensitive to this influence. 



" There is a decided decrease in tensile strength. The percentage loss varies 

 with the concentration of the sulphid and with the iron content of the cement. 

 The briquettes appear normal in every other respect, except in color. There is 

 no cracking nor distortion of any sort. In most cases sulphid may be present 

 in concentrations up to 1 gm. per liter without causing the tensile strength to 

 fall below United States Government specifications. Certain results indicate 

 that a colloid is formed by the action of sodium sulphid on the iron in the 

 cement. Based on the results of both chemical and physical observations, the 

 following explanations of the decrease in tensile strength are offered: (1) The 

 precipitated colloid forms films of inert material through the cement and inter. 



