G. H. F. Nuttall 
469 
the sliding grating is again opened widely. Air now passes in over the 
heated baffle plate and out through the grating above; the hot air 
circulating in the box dries the effects in about 30 minutes, when they 
can be removed and the lamp extinguished. Formalin (8 oz. of 40 % 
solution) may be added to the water in the tray if required, but for lice 
this is unnecessary. 
Hot •se-drawn Steam Sterilizers of various patterns are extensively 
employed. The Thresh Disinfector Company (4 Central Buildings, 
Westminster, London, S.W.) has supplied large numbers to the British, 
Colonial and American troops. These machines (Pis. X, XI, Figs. 3, 5) 
may therefore serve in a general way as types of such disinfectors except 
for the special feature that the jacket contains brine. 
Although the details of their structure and management will have to 
be mastered by those intending to use them, it will suffice here to mention 
the main principles of the construction. The sterilizer chamber is hori¬ 
zontal and double walled, a salt solution in the jacket 1 is brought to boil¬ 
ing point (ca. 220°F. = ca. 105°C.) and the steam evolved in the jacket, at 
a temperature of about 215° F., enters the chamber through a flue at the 
back; the steam operates at atmospheric pressure or under slight pres¬ 
sure, and expels the air from the chamber. After an exposure lasting 
usually half an hour, the steam is turned into the shaft and air is admitted 
to the chamber by opening a valve beneath the chamber door. The air 
traverses a bent pipe surrounded by boiling brine, being thereby heated 
before it enters the chamber. A small cistern, on the left outer side of 
the chamber and connected with the water supply, automatically renews 
the water in the jacket as the brine grows more concentrated through 
giving off steam. Calcium chloride was formerly used for the brine, but 
it caused difficulties by clogging the pipes and it has since been replaced 
by another salt. The cleaning of the boiler is a matter of some difficulty 
in all constructions of this kind. 
The following are amended instructions issued by the War Office 
concerning the use of Thresh Patent Current Steam Disinfectors (Fur¬ 
nace-heated), which the writer has slightly condensed, omitting the 
instructions for cleaning the machine (from Notes for Sanit,. Officers, 
B.E.F., France, 1917, p. 44, W.O. publication, 1918). 
1 The term “jacket,” applied to this and other forms of steam disinfectors herein 
described, refers to the interspace between the inner and outer walls of the chamber. 
These walls, either oval or round in cross section, are riveted at the ends to a 
ring, thus forming a closed space that is filled with steam which heats the inner 
chamber. 
