530 EXPERIMENT STATION RECORD. 



of the Infusoria, which are very troiililesome organisms in connection witli 

 water supplies, was remoA'ed by tlie use of copper sulphate at the rate of 1 part 

 to 12.0()(»,000 parts of water. The results, however, were not so satisfactory in 

 case of Diatouiace;e and green algt^. Moreover, it appears that after repeated 

 treatment with copper sulphate such organisms become less sensitive to its 

 action. Tender certain conditions copper sulphate seems to be very injurious to 

 tish. In one case reported 1 part of sulphate in 5,000,000 parts of water 

 destroyed large numbers of fish. There are conditions in both shallow and 

 deep ponds and reservoirs under which the diffusion of the copper is very 

 irregular and may remain for long periods locally concentrated. 



The use of copper and copper sulphate as a bactericide, etc. (pp. 289-338).- — 

 Tank and reservoir experiments on the use of copper sulphate and metallic 

 copper as a means of destroying bacteria, algjp, etc.. as well as studies of 

 sedimentation of copper sulphate, its combination with mineral and organic 

 matters, etc.. are reported in this article. The results show among other 

 things that while Bacillus coli and B. ti/phosus are occasionally killed by dilute 

 solutions of copper, these organisms may live for many weeks in water contain- 

 ing not more than 1 part of copper sulphate in 100,000 parts of water. It is 

 claimed that to insure the destruction of these germs 1 part of copper sulphate 

 to 1,000 parts of water must be used, and such an amount of copper gives a 

 strongly astringent taste to water. " In some instances, very dilute solutions 

 of copper sulphate, or colloidal copper absorbed from contact with clean metallic 

 copper, appear to have a decidedly stimulating effect on bacterial activity, caus- 

 ing rapid multiplication. . . . The two experiments made with sulphate of 

 alumina and ferrous sulphate seem to indicate that these salts are about as 

 efficient in destroying bacteria as copiter sulphate." 



In view of the uncertainty of the action of the copper sulphate under many 

 conditions, it is stated " that the use of any method of sterilization which is not 

 absolutely sure and effective is dangerous in ordinary hands, tending to induce 

 a false feeling of security, and leading to the neglect of ordinary precautions 

 which otherwise would be taken." 



The use of copper in the purification of water, L. F. Rettger and H. B. 

 Endicott (Enyin. ^Scws, 56 {1006), Xo. J7, pp. ',2'>, .'i26). — Experiments are 

 reported from which the conclusion is drawn that " in the absence of appreci- 

 able quantities of organic matter (and an unusual amount of carbonates) and 

 when the temperature is not too low (8-10° C), copper sulphate has a strong 

 germicidal action on Bacillns coli, B. typhi, the organisms of dysentery and 

 Asiatic cholera, and on hog and fowl cholera bacilli. At 20° C. they are de- 

 stroyed in dilutions of 1 to 400,000 and over, within a period of 24 hours. In 

 the natural condition of water in reservoirs, etc., the action is in all probability 

 much greater. When used intelligently, therefore, copper sulphate is a most 

 valuable agent in the purification of drinking water. It has been shown fre- 

 quently that small quantities of copper have no injurious action on man. Cer- 

 tain fish may be injured by it, but only in concentrations much greater than 

 those which are necessary to destroy the typhoid organism, etc." 



Sulphate of iron and caustic lime as coagulants in water purification, J. W. 

 Ellms (Emjin. Rec, 5'/ (1906), No. 16, pi>. 'i39-Ii'il, fifl- J).— The use of these 

 materials is discussed and their advantages explained. Of the latter the prin- 

 cipal are rapid sedimentation in turbid waters and consequent elimination of 

 plain sedimentation, diminished cost of purification, and a high degree of effi- 

 ciency, especially in the case of the turbid waters of the Middle West. 



Water softening and treatment, W. H. Booth {London: Archibald Constable 

 d Co., Ltd., 1906, pi). 324; rev. in Chem. Xeics, 94 {1906), Xo. 2.',35, p. 46). 



