216 PRACTICAL DIRECTIONS FOR DISINFECTION. 
DISINFECTION BY FORMALDEHYDE GAS. 
Recent experiments have demonstrated the valuable germicidal 
properties of formaldehyde gas. Owing to its superior germicidal 
value and non-toxic properties, it has to a considerable extent taken 
the place of sulphur dioxide as a gaseous disinfectant. In making 
practical use of this agent a suitable apparatus will be required. For 
the disinfection of a room with its contents, freely exposed for sur- 
face disinfection, one pound of formalin should be volatilized for 
each thousand cubic feet of air space—the time of exposure to the 
disinfecting action of the gas being not less than twelve hours. 
When paraform is used the amount required will be sixty grammes 
to one thousand cubic feet (Novy). In the absence of any appa- 
ratus satisfactory results have been obtained by the Department of 
Health of the city of Chicago, as follows: 
‘‘Ordinary bed sheets were employed to secure an adequate evaporatory 
surface, and these, suspended in the room, were simply sprayed with a forty- 
per-cent solution of formalin through a common watering-pot rose-head. A 
sheet of the usual size and quality will carry from one hundred and fifty to 
one hundred and eighty cubic centimetres of the solution without dripping, 
and this quantity has been found sufficient for the disinfection of one thousand 
«ubic feet of space. Of course, the sheets may be modified to any necessary 
number. . . . Surface disinfection was thorough, while a much greater de- 
gree of penetration was shown than that secured by any other method.” 
Formalin may also be used in the disinfection of rooms and their 
contents by spraying all exposed surfaces. 
Experiments made by Kinyoun and others show that formalde- 
hyde gas does not injure the color or textile strength of fabrics of 
wool, silk, cotton, or linen, and that it has no injurious action upon 
furs, leather, copper, brass, nickel, zinc, polished steel or gilt work. 
Iron and unpolished steel are attacked by the gas. 
DISINFECTION OF THE HANDS. 
The importance of a reliable method of disinfecting the hands of 
surgeons, obstetricians, and nurses after they have been in contact 
with infectious material from wounds, puerperal discharges, etc., is 
now fully recognized, and some surgeons consider it necessary to 
completely sterilize the hands before undertaking any surgical opera- 
tion which will bring them in contact with the freshly-cut tissues. 
The numerous experiments which have been made with a view to 
ascertaining the best method of accomplishing such sterilization of 
the hands show that it is by no means a simple matter to effect it, 
and especially to insure the destruction of microdrganisms con- 
cealed beneath the finger nails. Fiirbringer, in an extended series 
of experiments (1888), found that a preliminary cleansing with soap 
