Disinfection is the destruction of disease germs. Sterilization is
the destruction of all germs or bacteria, both the harmful and the
useful. Antisepsis is the checking or restraining of bacterial growth.
Deodorization is the destruction of odor. Unfortunately in practice none
of these processes may be complete. The agent may be of inferior quality,
may have lost its potency, or may not reach all parts of the mass treated.
A disinfectant or germicide is an agent capable of destroying disease
germs; an antiseptic is an agent merely capable of arresting bacterial
growth, and it may be a dilute disinfectant; a deodorant is an agent that
tends to destroy odor, but whose action may consist in absorbing odor or
in masking the original odor with another more agreeable one.[6]
[6] Those desiring more explicit information on disinfectants and the
principles of disinfection are referred to U. S. Department of Agriculture
Farmers' Bulletins 926, "Some Common Disinfectants," and 954, "The
Disinfection of Stables," and to publications of the U. S. Public Health
Service.
Of active disinfecting agents, heat from fire, live steam, or boiling
water is the surest. The heat generated by the slaking of quicklime has
proved effective with small quantities of excreta. Results of tests by the
Massachusetts State Board of Health[7] show that the preferable method
consists in adding sufficient hot water (120° to 140° F.) to cover the
excrement in the receptacle, then adding small pieces of fresh strong
quicklime in amount equal to about one-third of the bulk of water and
excrement combined, covering the receptacle, and allowing it to stand
1-1/2 hours or longer.
[7] Annual Report, Mass. State Board of Health, 1914, pp. 727-729.
Among chemical disinfectants a strong solution of sodium hydroxide
(caustic soda) or potassium hydroxide (caustic potash, lye) is very
effective and is useful in dissolving grease and other organic substances.
Both chemicals are costly, but caustic soda is less expensive than
caustic potash and constitutes most of the ordinary commercial lyes.
Chlorinated lime (chloride of lime, bleaching powder) either in solution
or in powdered form is valuable. For the disinfection of stools of
typhoid-fever patients the Virginia State Board of Health[8] recommends
thoroughly dissolving 1/2 pound of best chloride of lime in 1 gallon of
water and allowing the solution to cover the feces for at least 1 hour.
The solution should be kept in well-stoppered bottles and used promptly,
certainly within 2 or 3 days. Copper sulphate (blue vitriol, bluestone)
in a 5 per cent solution (1 pound in 2-1/2 gallons of water) is a good
but rather costly disinfectant. None of the formulas here given is to be
construed as fixed and precise. Conditions may vary the proportions, as
they always will vary the results. The reader should remember that few,
if any, chemical disinfectants can be expected fully to disinfect or
sterilize large masses of excrement unless the agent is used repeatedly
and in liberal quantities or mechanical means are employed to secure
thorough incorporation.
[8] Health Bulletin, Va. State Board of Health, June, 1917, pp. 277-280.
Among deodorants some of the drying powders mentioned below possess
more or less disinfecting power. Chloride of lime, though giving off an
unpleasant odor of chlorine, is employed extensively. Lime in the form
of either quicklime or milk of lime (whitewash) is much used and is an
active disinfectant. To prepare milk of lime a small quantity of water is
slowly added to good fresh quicklime in lumps. As soon as the quicklime
is slaked a quantity of water, about four times the quantity of lime, is
added and stirred thoroughly. When used as a whitewash the milk of lime is
thinned as desired with water and kept well stirred. Liberal use of milk
of lime in a vault or cesspool, though it may not disinfect the contents,
is of use in checking bacterial growth and abating odor. To give the best
results it should be used frequently, beginning when the vault or cesspool
is empty. Iron sulphate (green vitriol, copperas) because of its affinity
for ammonia and sulphides is used as a temporary deodorizer in vaults,
cesspools, and drains; 1 pound dissolved in 4 gallons of water makes a
solution of suitable strength.