884 EXPERIMENT STATION RECORD. I Vol. 37 



the total number examined 1,295 were from private supplies, of which 570 

 came from deep wells, 555 from shallow wells, 37 from cisterns, and 03 from 

 springs ; 785 of the private supplies were potable, 437 were bad, and 73 doubtful. 



Of the total number of 690 deep well supplies examined 552 were cla.ssed 

 as good, 103 as bad, and 35 of doubtful quality. Of the 569 shallow well sam- 

 ples analyzed but 243 were good, 291 were bad, and 35 were of doubtful quality. 

 Of the 84 springs analyzed 56 were found to be good, 21 bad, and 7 were of 

 doubtful quality. Of the 37 cistern waters examined but 14 were good, 18 were 

 listed as bad, and 5 were of doubtful quality. Nineteen of the 23 pond and 

 lake supplies examined were good and 4 were bad. 



Sterilization of water in the field, H. Penau {Jour. PJinnn. et Chim., 7. ser., 

 13 {1916), No. 12, pp. 877-385; abs. in Chan. Abs., 10 {1916), No. 19, p. 2^87).— 

 A process is described in which a solution of sodium hypochlorite containing 

 10 gm. of active chloriu per liter is prepared by double decomposition of cal- 

 cium hypochlorite with sodium carbonate and potassium permanganate and is 

 added at the rate of 0.5 liter per 1,000 liters of water. After 45 minutes 

 60 cc. of an aqueous 10 per cent solution of sodium thiosulphate is added. It 

 is found that colon bacilli are destroyed while the odor and taste of the water 

 are not impaired. 



Sewage disposal for school buildings in Ohio, R. S. Durrei.l and D. E. 

 Adams {Ohio Pub. Health Jour., 7 {1916), No. 8, pp. 326-3S8, pis. 6).— "The 

 purpose of this bulletin is to acquaint boards of education, and their architects 

 and engineers, in the general methods of sewage disposal for school buildings 

 not accessible to sanitary sewers, and in the design of the separate features in- 

 volved. It is not intended to provide standard working drawings for the con- 

 struction of .sewage-treatment plants for tliese buildings. The accompanying 

 plates illustrate not only the essential details but also the principal features to 

 be observed in preparing plans for submission. These plans illustrate sewage- 

 treatment plants which are applicable for schoolhou.se locations under tj-pical 

 Ohio conditions." 



The operation of sewage treatment plants for public buildings, l>. E. 

 Adams {Ohio I'lib. Health Jour.. 8 {1917), No. 1, pp. 20-30. figs. 2).— Instructions 

 as to the proper operation and maintenance of sewage-treatment phints for 

 public and private institutions and schools are given. 



The expansion and contraction of concrete and concrete roads, A. T. Gold- 

 beck and F. H. .Tackson, jr. (C7. S. Dept. Agr. Bui. 532 {1917), pp. 31, pis. 3, 

 figs. 16). — Laboratory and field tests begun in 1910 on expansion and contrac- 

 tion movements by concrete pavements are reporteil. These Included detailed 

 attention to the spacing, design, and movement of expansion joints. 



It was found that neat cement, when allowed to dry, first contracted rapidly, 

 then more slowly. The amount of contraction seemed to vary with the cement, 

 size of .specimen, and condition of atmosphere in which drying took place. The 

 amount at 28 days was about 0.1 per cent and at six months about 0.2 per cent. 



Mortar contracted on hardening in air and expanded on hardening in water. 

 The contraction in warm, dry air at 28 days was about 0.045 per cent for 1 : 2 

 and 1 : 3 mortar and at six months was 0.078 for 1 : 3 mortar and 0.085 for 1 : 2 

 mortar. The expansion in water was 0.01 per cent for 1 : 3 and 0.017 for 1:2 

 mortar at 28 days, and at six months 0.013 for 1:3 and 0.02 per cent for 1:2 

 mortar. 



Both 1:2:4 and 1:3:6 concrete contracted on drying in warm, dry air from 

 0.02 to 0.04 per cent at 28 days and from 0.04 to 0.07 per cent at six months. 

 When hardening in water an expansion of about 0.01 per cent took place at 

 28 days and at six months in 1:2:4 and 1:3:6 concrete. The riclinoss of the 



