PART VI. 
BACTERIOLOGY OF ANIMAL DISEASES 
Exercise 34. Preparation of General Disinfectant 
MATERIALS: 
A 20 per cent solution of corrosive sublimate (HgCl s ) in con- 
concentrated HC1 
2 liter stone jar 
Graduated cylinder 
As many of the pathogenic organisms produce diseases in man, as well as in 
the lower animals, an efficient disinfectant must be used in the laboratory 
when working with pathogenic organisms. 
A convenient disinfectant to use is corrosive sublimate or mercuric chloride 
(HgCl 8 ) in a 1 to 1,000 solution. 
1. Prepare 1.5 liters of corrosive sublimate, 1 to 1,000 from the 20 per cent 
solution on the desk. The 20 per cent solution is made with concentrated 
commercial hydrochloric acid (HC1) because mercuric chloride is quite insol¬ 
uble in water. 
2. Dilute the strong solution at the rate of 5 cc. to 1,000 cc. of water which 
gives approximately a 1 to 1,000 solution. Make the dilution in the stone jar 
and rinse the graduate well, pouring the rinsings into the solution. 
3. The solution is to be used on a sponge in wiping up the surface of the 
desk at the end of the laboratory period. If any material containing patho¬ 
genic organisms is accidentally spilled on the desk or floor, it should be covered 
at once with a cloth saturated with the mercuric chloride solution (1:1000). 
(a) Give the places where mercuric chloride cannot be used and 
explain why. 
(b) Is mercuric chloride a germicide or an antiseptic? 
(c) Why must gold rings and other jewelry not come in contact 
with solutions of mercuric chloride. 
