CL H. F. Nutt all 
481 
hot air is forcibly propelled through clothing and effects confined in a 
chamber (see p. 451). 
That heat, dry or moist (steam or boiling water), is superior to any 
chemical agents for the destruction of lice in clothing is held by Frank el, 
Meltzer, Seitz, Engelhardt, Wulker, Galli-Valerio, Legendre, Lelean and 
others who have had practical experience. In dealing with isolated cases 
it may, however, be more convenient to use other means. 
Recording the Temperature of Disinfectors. 
To be certain that the requisite temperature has been attained among 
effects subjected either to hot-air or steam disinfection various tests may 
be employed. Unless the objects are loosely hung in the space and 
a considerable margin of time is allowed, it is impossible, even in the case 
of current steam, to rely upon timing the exposure from the moment that 
the steam issues freely from the apertures of the heating chamber. Steam 
may issue freely without having necessarily penetrated the effects sus¬ 
pended in the chamber, and the same statement applies with regard to 
hot air. 
The most accurate way of determining the temperature is necessarily 
by thermometers. Contact or electric thermometers have been in use 
for many years for the purpose of signalling to the person in charge of 
the disinfector the moment when a desired temperature has been attained 
in that part of the disinfector in which the instrument has been placed. 
A crude method of determining if the temperature in a steam sterilizer 
has attained ca. 100° C. and been maintained for a certain time, consists 
in placing a medium sized potato in the chamber and seeing if it is 
cooked. In the same way a hen’s egg or lice and their nits have been 
employed to determine if the effects in a disinfestor have attained the 
desired lethal temperature. Neither of these methods commends itself. 
A temperature of 100° C. is unnecessarily high for louse destruction and 
test-lice and nits are totally unsuited for practical purposes. 
Bacot (4. vm. 1917, p. 151) has suggested the use of vessels containing paraffin 
of a known melting point as a means of registering whether or no a lethal temperature 
(60° C.) has been attained in the chamber. Jacobs (1918, p. 238) also advocates the 
use of paraffin sealed in tubes containing a bead which gravitates when the paraffin 
melts. Emrys-Roberts (4. V. 1918, p. 509) describes and figures a “wax thermometer.” 
Such methods are very unreliable and need not detain us. 
A very simple, accurate, cheap and practical method of determining 
if the lethal temperature (instead of using maximum thermometers) 
