390 EXPEEIMENT STATION RECORD. 



bacterial count. The absence of B. coli bacteria in well water after repeated 

 tests, however, does not necessarily indicate the absence of contamination. 



It was also found that B. coli bacteria are apt to occur rather widely in 

 surface soil, their numbers decreasing rapidly with depth. It is thought, 

 therefore, that surface wash bringing B. coli bacteria into well water does not 

 always contaminate it, but the more numerous these bacteria in well waters 

 and the more typical their acid-forming aciivities the greater is believed to be 

 the danger of disease contamination. It is considered advisable that the final 

 decision in this matter be governed by the location and surroundings of the 

 well. 



It is further concluded that the number and character of B. coli bacteria 

 present in well water may serve to indicate the efficiency of filtration. 



Further experiments on the usefulness of the Berkefeld filter for the puri- 

 fication of water supplies containing lead, P. Schmidt {Arch. Hyg., 82 {1914). 

 No. 8, pp. S51-354; abs. in Chem. Zcnthh, 1915, I, No. 11, p. 565).— In experi- 

 ments extending over four months to determine how long a Berkefeld house- 

 hold filter will continue to remove the lead from water contaminated with 

 lead, it was found that the lead in the filtrate gradually increased, reaching a 

 maximum after 22 days and a filtration of 3,000 liters of water. Thereafter 

 there was a gradual decrease of lead in the filtrate until it was reduced to 

 one-tenth. These results are taken to indicate that the iron in the water 

 formed a filtering layer of colloidal iron on the filter surfaces. The author 

 concludes, therefore, that the Berkefeld house filter is a useful aid in the 

 purification of such waters, especially if they contain traces of iron. Further 

 experiments showe^l that the lead was fixed on the surface of the filter in 

 hydroxid form. 



Automatic device controls hypochlorite application, E. E. Ludwick {Engin. 

 Rec, 72 {1915), No. 4, pp. lOS, 104, fiffs. 6). — An apparatus for automatically 

 gaging the amount of chemical to a varying flow of sewage in an institutional 

 sowa;:e-disposal plant is described. The works compri.se an Imhoff tank, in- 

 termittent siphon, sprinkling filter, chemical house, and a final settling tank. 

 The rise and fall of the sewage in the siphon chamber actuates the mechani.<?m. 



Water purification plants and their operation. M. F. Stein {New York: 

 John Wiley d Srm.t, 1915, pp. VIII+25S, pis. .?. figs. 10,3; rev. in Engin. Rec, 7S 

 (1915), No. 9, p. 268). — The purpose of this book is to give instructions for the 

 operation of water-purification plants. It has in general been the endeavor to 

 treat the subject with .special regard to the requirements of the nontechnical 

 operator of small plants, for whose benefit it has been attemptetl to include all 

 information and data required, such as instructions for preparing standard 

 solutions, making bacterial and chemical tests of the water, handling coagiilants. 

 wa.hing filters, keeping records?, etc. As a further aid, charts embracing the 

 computations necessary in determining the amounts of coagulants to be used 

 have been added. A chapter giving detailed descriptions of the various types 

 ol plants and their component parts, together with numerous examples, and a 

 chapter on the natural chemistry of water are also included. 



Highway laws of the United States {Good Roadf, n. .^er.. 10 {1915), No 6. 

 pp. 83-97). — This Is a digest of the laws governing the administration, con- 

 struction, and maintenance of highways in the several States. 



Papers presented at the Pan-American Road Congress {Good Roads, n. 

 ser., 10 {1915), No. 14, pp. 189-215). — These papers include the following: The 

 History and Future of Highway Improvement, by L. W. Page ; The Es.sentials 

 of Proper Laws for Highway Work, by E. A. Stevens : The Essentials of 

 Proper Laws for Highway Work, by A. N. .Johnson ; Highway Indebtedness. 

 Its Limitation and Regulation, by N. P. Lewis; The Determination of the 



