176 PHARMACEUTICAL BACTERIOLOGY. 



The salts are dissolved in six gallons of water; the glycerin, formalin and 

 eosin added and enough water to make up the ten gallons. 



E. Disinfection of Public Buildings and Public Conveyances. — Only rarely 

 will it become necessary to disinfect an entire large building, whether private 

 or public, and then the method of procedure is much the same as for the 

 sick room disinfection, already described, treating each room as though it 

 were independent of other rooms, excepting that inner connecting rooms 

 need not be closed and sealed. 



In disinfection, one important fact should never be lost sight of, namely, 

 that it is just as important to destroy the carriers of disease (flies, fleas, rats, 

 mice, and other animals), as the disease germs themselves. This is par- 

 ticularly important in public disinfection, so much so that it is a general 

 rule to always use a disinfectant which destroys the disease carriers, as sul- 

 phur dioxide. In the yellow fever district, for example, the chief fumigating 

 agent is burning Pyrethrum which is a sure death to the Stegomyia mosquito 

 as well as ,to other insects. 



Wherever and whenever practical therefore, sulphur dioxide should be 

 used for public disinfection. In many European cities the health depart- 

 ment is provided with portable generators which are run alongside the 

 building to be disinfected, the sulphur dioxide .generated and conducted 

 into the room, hall, cellar, or area way to be disinfected, by means of tubing. 

 This is the safest and most satisfactory way. If such apparatus is not 

 available, the flower of sulphur, sulphur candles, or liquefied sulphur dioxide 

 may be used (15 ounces to each 1006 cubic feet of space). Street cars, rail- 

 way cars, large public conveyances generally, may be disinfected much like 

 rooms, after being well sealed. A safe rule is to use double quantities of 

 the disinfectant for public conveyances, as compared with a sick room, be- 

 cause of the fact that it is difficult to seal such public conveyances well. 

 After the disinfectant has acted for a sufficient length of time (twelve to 

 twenty-four hours) , the place is opened, aired and then all of the wood work- 

 (of furnishings as well as the floor, walls and ceiling) is either washed or 

 sprayed with a i-iooo bichloride of mercury solution or a 3-5 per cent, 

 formalin solution. 



In such communicable diseases as have no animal carriers (other than 

 the patient himself) or where for obvious reasons such carriers are not pres- 

 ent, formalin will always be the preferred disinfectant, whether for private 

 or public disinfection, bearing in mind that heat and moisture are necessary 

 adjuncts to its use. Formaldehyde is not effective in a dry, cold atmosphere 

 because under those conditions the formalin is converted into solid polymer- 

 ized paraformaldehyde, which as such, is inert. 



Public or private disinfection by means of formalin may be carried out 

 as follows, the method selected depending upon time, place and opportunity. 



