43 



statements of Lima and Sen, that Culicidae beneath a film of 

 kerosine or petroleum are killed by the anaesthetic action of the 

 oil. Carbolic acid might sometimes be used in small, dirty pools, 

 as in a one-per-thousand solution of hquid carbolic acid, Culicid 

 larvae died in 20-25 minutes, and pupae in 85 minutes ; a weaker 

 solution (1 in 5,000) killed the larvae in two and a half hours, but did 

 not prevent the development of the pupae. While the larvae of 

 Dyliscus marginalis prey on those of Culex when confined with them, 

 they can only be regarded as auxiliaries in control under natural 

 conditions where other food occurs. 



Baerthlein (K.). Der Vondransche Heissluftapparat und seine Wir- 

 kungsweise gegenuber Laussen, Nissen und bakteriellen Keimen. 



[The Vondran Hot Air Apparatus and its Mode of Action on Lice^ 

 Nits and Bacterial Germs.] — Gentralhl. f. BakL, Parasit. u. Infek- 

 tionsJcr., Ite Aht. On'g., Jena, Ixxviii, no. 7, 18th November 1916, 

 pp. 527-557, 17 figs. 



In the Vondran hot-air apparatus intensive drying of the articles 

 treated is the principle adopted for destroying lice and their eggs, as 

 Avell as bacterial germs. An electric blower beneath the twin dis- 

 infecting chambers drives the heated air upwards through openings 

 in their floors, so that garments hanging within are blown out and 

 a uniform degree of heat is attained everywhere, a result peculiar 

 to this machine and one very advantageous in practice. The air in 

 the chambers is changed 43 times a minute. In one test it was found 

 that with the air in the free space within a chamber at 186° F., the 

 temperature in the centre of the mass of garments was 180°-187° F., 

 the difference being thus very small. A uniform high temperature is 

 quickly reached. In one test with a fully loaded chamber the air 

 temperature was raised from 80° F. to 188° F. in six minutes, and 

 to 198° F. in 11 minutes. To destroy hce, 45 minutes at 178° F. and 

 40 minutes at 186° F. suffice with this machine. Deahng with 

 apparatus where the air is in a state of rest, Heymann stated that 

 about two hours are required to raise the temperature to 178° F.-195° 

 F., so that six hours would be needed to effect the destruction of 

 lice. For practical work with the Vondran machine, temperatures 

 of 178°-186° F. are the best. Only two minutes are needed to switch 

 the hot-air blast from one chamber to the other, and while one is 

 in use the other may be unloaded and reloaded. The articles to be 

 disinfected are hung on a framework which is pushed into the 

 chamber at one end, and after the operation is completed the frame 

 is run out at the other end of the chamber and unloaded there, so 

 that the risk of contact with infested garments is avoided. At a 

 temperature of 186° F.,64 complete sets of military equipment can 

 be dealt with per hour, or 1,536 in 24 hours, at a cost of about 

 one farthing per set. There was no trace of damage to articles 

 made of leather, fur, plush or velvet. The furnace is lighted two 

 hours before the machine is required for work, the articles to be treated 

 are arranged on the framework and pushed into the air chamber, 

 the stream of heated air is admitted, and the thermometer is watched. 

 The preliminary warming up takes 15 minutes, and disinfection 

 30 minutes. Overheating must be avoided. In the meantime, the 



