324 LABORATORY WORK. 
of formalin; /. one drop of carbolic acid solution (1-20); k. four drops of 
carbolic solution; /. ten drops of carbolic solution; m. 1/8 gram of borax; 
n. 1/4 gram of borax. Place all test-tubes in the incubating oven and ex- 
amine at intervals to see which of them undergo putrefaction and which are 
thoroughly disinfected. Note how very much more efficient some disin- 
fectants are than others. Which proves to be the most efficient? It is 
well in this experiment to close the tubes loosely with a cork to prevent 
evaporation of the volatile disinfectants. 
The Use of Disinfectants. The ordinary use of disinfectants is in con- 
nection with disease, their purpose being to destroy disease germs and 
thus to prevent the spreading of disease. They are sometimes used for 
other purposes, such as reducing offensive odors, etc., but primarily they 
are for the checking of infection. There are various methods of killing bac- 
teria which may be applied under different conditions. Heat, sunlight, 
drying, chemicals, and disinfecting gases are all of use in certain connections. 
The determination of which is to be used will depend upon conditions. 
The first problem to be settled in all cases of disinfection is when and 
where the disinfecting agent should be applied to produce the desired re- 
sults. A few practical suggestions as to methods may be of value. 
The Person. Of all sources of danger the one of greatest importance is 
the person ; first the patient, especially after recovery, when he is to mingle 
with other people, and secondly the attendants on the patient. Disin- 
fection of the patient during the disease is rarely possible, though his skin 
should be kept clean by bathing in water to which a little glycerin is added. 
The nurse, however, should keep scrupulously clean. Her hands should 
be carefully washed in soap and water followed by strong alcohol, or the 
corrosive sublimate solution above described. Such cleaning should follow 
every time that the nurse handles the patient or any article of clothing or 
eating utensils touched by the patient. Other parts of the body also need 
attention, but not so frequently. The hair should be kept in a cap to pre- 
vent its getting contaminated, for it is difficult to clean and almost impos- 
sible to sterilize it. When the patient has recovered so as to leave quaran- 
tine he should receive the same treatment. 
Carbolic acid solution is especially useful as a skin wash, and is extremely 
valuable in cases of cuts or skin abrasions. If all cuts and bruises be 
washed at once in the carbolic solution (1/20), many a serious sore and 
many a case of blood poisoning will be prevented. Every household 
should have a carbolic acid solution on hand for such purposes. 
Clothing, Bedding, Etc. These articles offer a difficult problem. The 
following general directions may be given. 
Burn everything which is of no great value. 
Boil in water all articles that can be so treated. The boiling should 
continue for half an hour and will be sufficient for complete disinfection. 
Steaming is sometimes employed for articles too heavy for boiling, such as 
mattresses and carpets. This requires special apparatus and can rarely be 
performed at home. Any article that can be soaked in water may be dis- 
infected by soaking it three or four hours in water containing one part for- 
