1909.] 



The Germicidal Action of Metals, etc. 



87 



Note. — Subsequent to the above experiments, further analyses have been 

 made, using boiled distilled water in the place of tap water. It was found 

 that zinc in contact with distilled water, without the bubbling process, 

 has a decided germicidal action. Copper has a variable effect, never as 

 strong as that exhibited in the foregoing experiments. Aluminium usually 

 corresponds in effect to that exhibited by plain boiled distilled water, which 

 causes, in an hour, slight reduction in the number of organisms. 



Away from the metal — that is, in water which has been in contact with 

 the metal for one hour and then placed in a clean vessel — zinc water 

 (distilled) still causes a reduction in the number of organisms. It will be 

 seen that this is in line with the observations of Behring noted in our 

 introductory paragraph. It is difficult to ascribe this to anything but the 

 direct effect of the metal in solution, and yet, only the minutest traces of 

 the metal are present, quantities which in tap water could hardly be 

 responsible for the effects produced, and indeed would not produce them. 



As bearing upon these somewhat divergent results it may be recalled, 

 as a matter of familiar knowledge, that the action of distilled and of acid 

 waters upon copper and other metals differs from that of the (usually) 

 alkaline tap waters. 



BIBLIOGRAPHY. 



(1) H. T. Barnes and G. W. Shearer, "A Hydrogen Peroxide Cell," 'Journal of 



Physical Chemistry,' 190,8, vol. 12, p. 155; "The Production of Hydrogen 

 Pero.xide from Aluminium and Zinc," ' Journal of Physical Chemistry,' 1908, 

 vol. 12, p. 468. 



(2) Behring, 'Zeitschr. f. Hygiene,' 1890, vol. 9, p. 482. 



(3) Bolton, "The Effects of Various Metals upon the Growth of Certain Bacteria," 



' International Medical Magazine,' 1895, vol. 3, p. 812. 



(4) H. W. Clark and S. De M. Gage, 'Journal of Infectious Diseases,' Supplement, 



No. 2, 1906, p. 175. 



(5) M. Picker, 'Zeitschr. f. Hygiene,' 1898, vol. 29, p. 1. 



(6) F. C. Harrison and J. Van der Leek, "^sculin Bile Salt Media for Water 



Analysis," ' Centrlbl. f. Bact.,' Abt. 2, 1909, vol. 22, p. 547. 



(7) Leedham -Green, 'The Practitioner,' 1907, vol. 78, p. 372. 



(8) Miller, ' Verhandl. d. Deutsch. Odont. GeselL,' vol. 1, p. 34. 



(9) Eaulin, ' Annales des Sciences Naturelles Botanique,' 1870. 



(10) Van Der Dois, ' Zeitschr. f. Physik. Chem.,' 1898, vol. 24, p. 351. 



