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need no special preparation beyond the ordinary closing of doors and 
windows. Pasting, caulking, or chinking of ordinary cracks and 
crevices is not necessary. The doors of lockers and closets and the 
drawers of bureaus should be opened. In this apparatus use formalin 
(40 per cent) , with the addition of a neutral salt, such as calcium chlo- 
ride (20 per cent). The gas must be evolved under a pressure not less 
than 45 pounds. After the gas is separated from its watery solution 
the pressure may be allowed to fall and steam projected into the com- 
partment to supply the necessary moisture. Use not less than 10 
ounces of formalin per 1,000 cubic feet, and keep the room closed for 
three to twelve hours after the completion of the process. For large 
rooms the gas must be introduced at several points as far apart as 
possible. It is applicable to the disinfection of clothing and fabrics 
suspended loosely in such a manner that every article is freely acces- 
sible to the gas from all directions. 
168. Lamp or generator. This method requires an apparatus pro- 
ducing formaldehyde by a partial oxidation of wood alcohol, and in 
using it the room or apartment should be rendered tight as practi- 
cable. Oxidize 24 ounces of wood alcohol per 1,000 cubic feet, and 
keep the room closed for six to eighteen hours, in accordance with the 
provisions of paragraph 165. This method leaves little or no odor. 
When applied to clothing and textiles, the articles should be sus- 
pended in a tight room and so disposed as to permit free access of the 
gas. (See also Par. 166.) The wood alcohol should be of 95 per cent 
strength, and should not contain more than 5 per cent of acetone. 
169. Spraying. The formalin (40 per cent) should be sprayed on 
sheets suspended in the room in such a manner that the solution 
remains in small drops on the sheet. Spray not less than 10 ounces of 
formalin (40 per cent) for each 1,000 cubic feet. Used in this way a 
sheet will hold about 5 ounces without dripping or the drops running 
together. The room must be very tightly sealed in disinfecting with 
this process, and kept close not less than twelve hours. The method 
is limited to rooms or apartments not exceeding 2,000 cubic feet. The 
formalin may also be sprayed upon the walls, floors, and objects in 
the rooms. 
170. Formaldehyde with dry heat in partial vacuum. This 
method has superior penetrating powers and is specially applicable to 
clothing and baggage. The requirements of this method are (1) dry 
heat of 60° C. sustained for one hour; (2) a vacuum of 15 inches; (3) 
formaldehyde evolved from a mixture of formalin with a neutral salt, 
in an autoclave under pressure, using not less than 30 ounces of for- 
malin (40 per cent) for 1,000 cubic feet; and (4) a total exposure, under 
these combined conditions, of one hour. 
171. The stated times of exposure to sulphur dioxide and formalde- 
hyde are sufficient to destroy bacterial infection due to non-spore- 
