488 EXPERIMENT STATION RECOED. IVul. 37 



pipe made of redwood, or of coated fir or piue, etc.. manufactured according 

 to present-day standards, as indicated by the siiecifications covering this class. 

 Class C — pipes of this class will be used for temporary work only and may be 

 manufactured from redwood, fir, pine, or any other wood, with or without 

 coating, as desired." 



Analyses of Fargo city water supply, R. Hulbert {Xorth Dakota Sta. Spec. 

 Bill., 4 {1911), No. 12, pp. 338-3^1). — Chemical and bacteriological analyses of 

 samples of water from the Red River and of the same after undergoing puri- 

 fication at the Fargo city filtration plant showed that the purification proces.s 

 renioved better than 99 per cent of the organisms present in the raw river water. 



Investigations on the filtration of drinking water. — I, The theory of slow 

 sand filtration, K. Kisskai.t (Ztschr. Hyg. n. Infektionskranlc, 80 (1915), No. 

 1, pp. 57-64, flO- !)• — Experiments are reportetl on the slow filtration of water 

 through sand in which it was found that the addition of potassium cyanid killed 

 the protozoa in the filter but did not injure the bacteria and thus destroye<l the 

 purifying action of the filter almost completely for some time. It is concluded, 

 therefore, tluit the greatest part of the purification process of slow-sand filtra- 

 tion is due to the protozoa. 



A bibliography is appended. 



A new process for the chemical sterilisation of drinking water in the 

 field, M. Rhein {Ztschr. II yg. u. Infcktiunsknink., 78 {191 i). No. S, pp. 56t- 

 570, fig. 1). — It was found that by the addition of 2.1 cc. of antiforniin and 

 1.1 cc. of 2.J per cent hydrochloric acid to 1 liter of contaminated water which 

 had been filtered through wadding coli bacteria were kille<l In five minutes at 

 the rate of 4.000,000 {)er cubic centimeter of water. The chlorln was removtHi 

 from the treated water by means of a tablet containing 1.7 gm. of sodium bicar- 

 bonate and 0.45 gm. of sodium thlosulphatc. The treated water had then a 

 slightly alkaline taste, was clear and oilorle.ss. and was found safe to drink. 

 Sodium sulphite was also found to l)e effe<"tive for the removal of the chlorin 

 when bathing water was treated. 



A bibliography is appended. 



The manner cf action of biological sewage purification media, T. Mksseb- 

 scuMiDT {Zt.ichr. Hyg. u. Infcktionskrank., 78 (Wl-i), A'o. 3, pp. ^75-488, figt. 

 2; 80 {1915), No. S, pp. 4^7-456). — From a comparison made in the laboratory 

 of the so-called absorption and nitrification theories of the action of .<e\vage 

 purification media, it is concluded that the nitrification theory is not entirely 

 correct and that the action of biological fillers may be explained primarily on 

 the grounds of absorption. Nitrification Is considered merely a part <>f the 

 total process. 



Further experiments showed that In a perfectly purified sewage the .-ilbuml- 

 nous substances are so completely destroyed that they have lost their antigen 

 character. A third set of experiments In which a natural and highly infective 

 sewage was jiut through tlie biological filter process in the laboratory showed 

 that under optinmm conditions a complete sterilization could not be obtained. 



A bibliography is appended. 



A new type of trickling filter, G. G. Nasmith {Survcynr, 51 {1917), N9. 

 130,3, pp. 4> 5, fig. 1). — Experiments on a trickling sewage filtpr made of wood 

 lath are reported. 



" The laths of the lowest layer were laid pai-allel to one another, the space« 

 between the laths being a little less than the width of the laths themselves. A 

 second layer was laid on top of this and at right angles to it, with the same 

 interspace. A third row was laid parallel to the bottom row. but In such n 

 manner that th;- lisths covoietl the spaces left betworn the Infhs of the lower 



