Gr. H. F. Nutt all 
539 
put on cloth immediately after it was impregnated were all killed 
in 44 hrs, but none were killed after an interval of 24 hrs * 24 % 
were killed by 5-7 hrs exposure after an interval of 24 hrs and none 
after an interval of 72 hrs. 
(e) With safrol and Oxford grease (Expts 294, 325) or with 
chlor-cresol added thereto (Expt 291) the impregnated cloth had 
no effect on lice after 24 hrs; an unpromising result. 
(/) With soap emulsion. Expt 292: still killed of the lice 
after an interval of 24 hrs. 
(g) With soft soap>. Expt 290: of the lice killed after an 
interval of 48 hrs. Expts 317-319: only the lice that were killed 
are recorded from the protocols, but many were feeble and practi¬ 
cally dying; in tests made 48 hrs after anointing the cloth 27 %, 
13 % and 3 % of the active lice' survived in the three experi¬ 
ments. In Expt 320: a test made after an interval of 168 hrs 
resulted in the death of 63 % of the lice after an exposure of 
9 brs, whilst in parallel Expt 321 81 % were killed by crude un¬ 
whizzed naphthaline and soap. If Expts 311, 312, 315, 316, made 
with naphthaline only, are compared with the foregoing, made 
with the soap mixture, it will be seen that the addition of soap 
greatly increases the potency of the naphthaline; Bacot attributes 
this to the spreading of the soap increasing the vapourizing area 
and bringing some contact action into play by its spreading in 
the cloth. When Bacot sweated in consequence of exercise, whilst 
harbouring the experimental lice on his person, the lethal effect 
was increased. 
(h) With soft soap and Kieselguhr ( =diatomaceous earth, as 
vehicle). Expts 293, 323: all lice were killed in 4| hrs after a 24 hrs 
interval in one case whilst 31 % were killed in 4-5 hrs after an 
interval of 144 hrs in the second case. The Kieselguhr seems there¬ 
fore to be a useful ingredient since the evaporation of naphthaline 
is thereby further retarded. 
(i) With vaseline and soft soap. Expt 306: records of the lice 
killed in 4 hrs after a 24 hrs interval. 
Comments. The mixture (b) has been supplied to the troops in 
France, but experiments demonstrate that it is inferior to naph¬ 
thaline alone, the effect of the grease being practically nil. 
Oxford grease or powder 1 added to naphthaline acts merely as 
a diluent. Peacock (MS. Report, W.O. i. 1918) reports that lice 
1 Merely a proprietary name. In no way associated with the town of Oxford, 
Parasitology x 35 
