250 ANNUAL OF SCIENTIFIC DISCOVERY. 



2. Chloride of Lime has been very largely used in tKe city during 

 the recent epidemic of cholera. The inspectors have sprinkled it 

 upon the floors of the houses occupied by the poor, and have scat- 

 tered it about the cellars and yards. In some cases it has been 

 used with water for washing the paint-work and the floors of 

 rooms. Altogether, indeed, with an average staff of 45 men, we 

 have used rather more than 7 tons of chloride of lime in this man- 

 ner in disinfecting every week about 2,000 of the worst class of 

 houses in the citv, and the results have been most satisfactory. 



%j / 



3. Carbolate of Lime, which is a mixture or rather a chemical 

 compound of carbolic acid and lime, has been used in many cases 

 where the smell of chloride of lime or its bleaching action has 

 been objected to. It has been used by dusting it by means of a 

 dredger over the floors of rooms and cellars : but as the disinfect- 

 ing power of this substance is destroyed by chloride of lime, it is 

 of great importance that they should not be used together. The 

 carbolate of lime which we have employed contains 20 per cent, 

 of carbolic acid. It is essential that this should be its minimum 

 strength, or its power is not sufficiently efficacious. The strength 

 of it may be ascertained by treating 100 grains of it with sufficient 

 muriatic acid, diluted with its own bulk of water, to dissolve the 

 lime, when the carbolic acid is set free, and floats upon the liquid ; 

 this, when collected, should weigh 20 grains at least. The advan- 

 tage of carbolate of lime is its continuous action ; for the carbonic 

 acid of the air slowly lets loose the carbolic acid, which diffuses 

 itself through the atmosphere in sufficient quantity to act as a dis- 

 infectant, and it does not destroy the color of clothing. 



4. Carbolic Acid has been used as the sole agent of disinfection for 

 privies, drains, and sinks, and for the sewers and the public roads. 

 In the former case it has been used in its concentrated state by 

 pouring it at once into the privy or drain, but in the latter case it 

 has been diluted with about 2,000 times its bulk of water and 

 sprinkled by means of the water-carts upon the public way. In 

 this manner about 1,000 gallons of carbolic acid have been used in 

 the city thoroughfares ; and the acid getting into sewers, we 

 have observed that the usual decomposition of sewage has been 

 arrested, and instead of a putrefactive change with the evolution 

 of very offensive gases, the sewers have been charged to a slight 

 extent with carbonic acid and marsh gas. As there are many coal- 

 tar acids now sold for carbolic acid, it is of importance that the 

 adulteration should be recognized. This may be done by observ- 

 ing the strength of the soda solution which will dissolve the tar 

 acid. All the inferior acids are insoluble in a weak solution of 

 caustic soda. 



5. Chloride of Zinc (Sir William Burnett's fluid, or, as it is some- 

 times called, Drew's disinfectant) is well suited for the disinfec- 

 tion of the discharges from sick persons, but it is hardly applica- 

 ble to any other purpose. The liquid should be of a proper 

 strength, as having a specific gravity of 1,594, water being 1,000, 

 and it should contain about from 50 to 54 per cent, of solid 

 chloride of zinc. A tablespoon ful of this liq'uid is sufficient to dis- 

 infect each discharge from the body. 



