434 
Combating Lousiness 
instantaneously by immersion in water at 90-100° C. and that even an 
exposure of 5 seconds at 70° C. is likewise fatal. Therefore, allowing a 
margin of safety under practical conditions, a thorough scalding of 
verminous effects or their immersion in hot water at about 70° C. for 
a minute or two will amply suffice to destroy lice. Since, however, nits 
and lice are killed at 55° C. in 10 minutes and this degree of heat perhaps 
causes less shrinkage in flannels, the exposure at the lower temperature 
might be practised with advantage under adequate control. 
( b) Exposure to steam. 
Steam Jet. 
Nits, 24 hours old, were exposed for 1 minute in a steam jet at 90° C. 
They all became coagulated (whitened) and promptly collapsed (Nuttall). 
Heymann (8. in. 1915, p. 53) states that a steam jet) as obtained from 
a railway train, will kill nits and lice promptly if applied once or twice to 
clothing. There is no doubt but that Heymann is correct in his statement. 
Steam Sterilizer. 
Although it is evident that steam at 100° C. will kill lice and nits 
instantly , both Kisskalt and Friedmann state that a 5 minutes’ exposure 
is necessary, and Galli-Valerio gives the period as 2-5 minutes. When 
steam sterilization is applied to clothing in practice the exposure must 
necessarily be lengthened to insure the penetration of the steam into the 
clothes and their folds, seams, pockets, etc. The following table summar¬ 
izes the practical observations of various authors as to the time required 
to kill lice and their nits. 
Temperature 
0° C. steam 
Length of 
exposure 
Authority 
(reference 
sterilizer 
in minutes 
Load 
Kind of sterilizer, etc. 
see p. 435) 
115° 
25' 
“Clothes” 
Adapted from brewery boilers 
in Flanders. After steaming, 
shake clothes which are warm 
and dry and ready to put on 
at once 
Honck 
101-6° 
101-6° 
45' 
30' 
100 garments 
60 blankets or equi¬ 
valent ... 
Thresh disinfector 
Peacock 
Lelean 
90-100° 
45' 
“Clothes” 
Not stated 
Giese 
100° 
100° 
30' 
30' 
) 9 • • • 
‘‘ Clothes, blankets 
and linen” 
Serbian experience, barrels ... 
Uhlenhuth 
Slammers 
100° 
20' 
“Clothes” 
Not stated . 
Legendre 
100° 
10' 
99 ••• 
99 * * * "• 
Jeanneret- 
Minkine 
It is a 
common 
experience to see lice survive when insufficient time 
has been 
allowed 
for the steam to penetrate clothing. I 
know of 
