92 A MANUAL OF BACTERIOLOGY 



Exercise 132. Preparing a Disinfectant 



In all work where pathogenic bacteria are employed great 

 care must be used to avoid infection. Apparatus and media should 

 be promptly and thoroughly sterilized after having been used. 



The disinfectant of greatest utility is mercuric bichloride, or 

 corrosive sublimate, in a solution of 1 : 1000. Prepare 2 liters 

 of a 1 : 1000 solution of mercuric bichloride and place it in a 

 jar on your table. The solution is readily made by dissolving 

 20 g. of mercuric bichloride in 100 cc. of commercial hydrochloric 

 acid. 5 cc. of this acid solution in 1 liter of water makes a 

 1 : 1000 solution. 



As soon as discarded all cultures should be placed in this jar. 

 Be careful to see that the test-tube cultures sink, drop in the 

 used cotton plugs, open Petri dishes and drop them carefully in. 

 The following day remove the dishes and wash them. 



Carefully wipe up the table top with a towel soaked in 1 : 1000 

 solution from the siphon bottle on the general table. If cultures 

 or infectious material are spilled on the floor, wipe them up in 

 the same way. Wash the hands first with 1 : 1000 bichloride and 

 then with soap and water. 



When sterilizing the platinum needles which have infectious 

 material upon them hold high above the flame until the material 

 is dry before bringing it into the flame. This prevents sputtering, 

 which may throw the material off before the germs are killed. 

 Some bacteriologists employ metal tubes into which the needles 

 are thrust for heating. 



Exercise 133. Anthrax (Splenic Fever) 



This is one of the best-known and longest-studied of bacterial 

 diseases. It is pathogenic for man and domestic animals. For 

 many years it was known as Wool Sorter's Disease, because of 

 its prevalence among those who handle wool. 



The first proof that a disease may be caused solely by a 

 bacillus was obtained, in the case of anthrax, by Robert Koch in 

 1876, although others had previously seen microscopical rods in 

 the blood of diseased animals. 



