326 A MANUAL OF BACTERIOLOGY 



Kingzett, the most active antiseptic and germicide 

 among these classes of substances. 



Edington l has shown that mercuric chloride dis- 

 solved in water (rendered acid) in the proportion of 

 1 part in 1000 destroys the spores of Bacillus 

 anthracis in fifteen minutes, for the spores after this 

 treatment and subsequent washing in sterilised 

 water refused to grow on nutrient agar-agar. Mer- 

 curic chloride also destroys Bacterium allii, Micro- 

 coccus tetragonus, M. prodigiosus, M. violaceus, Sarcina 

 lutea, Bacillus subtilis, and other microbes. 2 Perhaps 

 a more powerful germicide than mercuric chloride 

 is mercuric iodide; and Woodhead 3 has used a 

 solution containing ' 1 gramme of mercuric iodide 

 with a slight excess of potassium iodide in 1000 cc. 

 of distilled water.' 



Chlorine gas and the vapours of bromine and 

 iodine are powerful germicides, readily destroying 

 most microbes. According to the author's 4 investi- 

 gations, the germicidal power of the three halogen 

 elements is inversely as their atomic weights (Cl = 

 35*5; Br = 80; I = 127), i.e. chlorine is the most 

 powerful germicide, then bromine, and finally iodine. 

 In fact, the germicidal power of these elements 

 coincides with their chemical affinities ; but this 

 remark does not apply to the salts containing these 

 elements. Iodine, 5 potassium iodide, sodium iodide, 



1 British Medical Journal, 1889. 



2 Griffiths' Researches on Micro- Organisms, p. 204. 



3 Proceedings of Royal Society of Edinburgh, vol. xv. p. 246. 



4 Loc. cit., p. 182. 



5 Griffiths in Proc. Roy. Soc. Edinburgh, vol. xv. p. 37. 



