LABORATORY STERILIZATION 251 



what more expensive, and bulky to transport. Paraform dissolved 

 in warm water, in the proportion of two ounces of the former to half 

 a pint of the latter may be used in place of formalin either in the 

 permanganate method or the volatilization method described in the 

 foregoing. 



Attempts have been made to combine paraform and sulphur in the 

 form of candles or pastilles for purposes of disinfection. Such pre- 

 parations are valueless so far as the generation of formaldehyde is 

 concerned, 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 it is now used chiefly for insecticidal fumigation. 

 The products of combustion are SO 2 and SO 3 , both gases; in the 

 presence of moisture they have considerable germicidal activity, but 

 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 germi- 

 cide is restricted to the holds of ships, to warehouses and similar struc- 

 tures, 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 

 one to two feet in diameter and from three to six inches high. These 

 are placed in pans containing about two 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 three inches deep in the pot and 

 should slope gently from the edges of the pot to the center, where 

 a crater is hollowed out and filled with an 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. 



Liquid 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. 



