48 LICE AND THEIR MENACE TO MAN 



reinfestation. All this has led often in the past 

 to disinfestation falling into disrepute among the 

 men. 



Momentary immersion in boiling water of an 

 individual louse or egg kills it at once. It would 

 be as impossible for a nit to hatch after this as it 

 would be for a chicken to emerge from a boiled 

 hen's egg. Boiling the most verminous garment 

 for one minute will render it completely harmless, 

 and there can be no better or safer treatment for 

 an article the fabric of which would not be 

 damaged by this drastic process. As, however, 

 woollen garments shrink under this treatment, it 

 is necessary for them to use a lower temperature 

 and to allow a longer time for the penetration of 

 the heat. An analogous case is the boiling of a 

 hen's egg. If this is immersed in boiling water for 

 four or five minutes it becomes " hard-boiled." 

 If it is placed in water at a temperature of 165 F. 

 for a sufficiently long time its contents coagulate 

 equally and it becomes " hard-boiled." In the 

 first case where much heat is available penetra- 

 tion is more quickly, attained than in the latter, 

 where there is less heat available, but the result 

 in the end is the same. So with lice far lower 

 temperatures than that of boiling water may be 

 used to kill them, but an increasing time must be 

 allowed for the operation the lower the tempera- 

 ture used. 



It makes little difference to the result whether 

 the heat is dry or wet, that is, whether the opera- 



