LABORATORY STERILIZATION 281 
offers no advantages over formaldehyde, except that it occupies much 
less space. Special lamps have been devised to liberate formaldehyde 
from it in the gaseous state, but the efficiency of the method is not 
greater than the permanganate method, and the apparatus is some- 
what more expensive, and bulky to transport. Paraform dissolved 
in warm water, in the proportion of 2 ounces of the former to | pint of 
the latter may be used in place of formalin either in the permanganate 
method or the volatilization method described in the foregoing para- 
graphs. 
Attempts have been made to combine paraform and sulphur in the 
form of candles or pastilles for purposes of disinfection. Such prepa- 
rations are valueless so far as the generation of formaldehyde is con- 
cerned, because the products of combustion of this substance are carbon 
dioxide and water. 
3. Sulphur.— Sulphur was formerly highly regarded as a gaseous 
disinfectant, but is is now used chiefly for insecticidal fumigation. 
The products of combustion are SO2 and SO3, both gases; in the 
presence of moisture they have considerable germicidal activity, })ut 
little penetrating power. 
Sulphur dioxide and trioxide are vigorous bleaching agents; they 
destroy fabrics, fine furnishings and are injurious to painted or var- 
nished surfaces. Consequently, the usefulness of sulphur as a ger- 
micide is restricted to the holds of ships, to warehouses and similar 
structures, where the destruction of vermin is an important factor in 
the disinfecting process. 
At least 5 pounds of sulphur for each 1000 cubic feet of space to 
be disinfected are placed in a broad, shallow iron pot, preferably 
from 1 to 2 feet in diameter and from 3 to G inches high. These are 
placed in pans containing about 2 inches of water, both to prevent 
damage if the pot cracks during the burning process, and to supply 
moisture essential to the success of the disinfection. The sulphur 
should be not more than 3 inches deep in the pot anrl should slope 
gently from the edges of the pot to the center, where a crater is hol- 
lowed out and filled with 1 ounce of alcohol to start combustion. The 
sulphur burns slowly, and all cracks, doors and windows should be 
sealed with paper and paste to prevent escape of the fumes. At least 
twelve hours should be allowed before the room is opened. 
Li({uid sulphur dioxide is sometimes used in place of burning sul- 
phur; the cost is several times that of burning sulphur, and for the 
practical disinfection of rooms it is rarely used. 
4. Chlorine Gas. — Chlorine gas, particularly in humid atmospheres, 
possesses considerable germicidal power, but its extremely corrosive 
action upon fabrics and furnishings has materially restricted its field 
of usefulness for practical disinfection. It is widely used, however, 
for the disinfection of waters, 0.25 to 1 part of available chlorine to 
1,000,000 parts of water usually suflfices unless much organic matter is 
present. 
