92 
It would therefore appear that in planting out these diseased 
saplings too much care cannot be taken to observe their state of 
vitality with a view to transplanting them when this is at its greatest, 
or at any rate to avoid doing so, when it is at its lowest ebb. 
EWING SMITH. 
Bau. 1 8th February , 1908. 
EXTERMINATION OF RATS IN 
PADDY FIELDS. 
The destruction of paddy in the Kuala Kangsar district was 
reported to the Department of Agriculture on the 7th January last. 
Enemies other than rats were suspected and a careful examination 
in the laboratory of material forwarded by the Assistant District 
Officer, Kuala Kangsar, failed to find the presence of any plant 
or animal parasite. A personal examination forced me to agree 
with the Assistant District Officer that the damage was due to the 
rats alone. 
The Director of Agriculture suggested experiments with carbon 
bisulphide. These were carried out at Kuala Kangsar on the 10th, 
11th and 12th of February. 
Carbon bisulphide is a liquid substance with an unpleasant smell. 
It vaporises fairly quickly in air. Its vapour is a strong poison, and 
has a comparatively low ignition point, said to be 248° F. ; mixed 
with air it forms an explosive compound if heated sufficiently. The 
vapour is heavier than air so that it goes downwards and will 
penetrate to the deepest part of a rat’s tunnel. 
The method of application was to close the two ends of the 
tunnel, drive a hole into it near one end with a sharp stick, drop 
in a plug of cotton wool soaked with carbon bisulphide and close 
the hole thus made. The carbon bisulphide on the cotton wool 
would evaporate, diffuse through the tunnel and poison all rats in it. 
Owing to the hardness of the ground it was mostly found impossible 
to bore a hole in the way mentioned ; instead the plug of cotton 
wool was pushed as far as possible with the hand or a stick into 
the tunnel, the end being immediately and quickly closed with a 
little earth ; this method was found to be as good as boring a hole, 
besides being much simpler. The plug of cotton wool was, as a 
rule, nearly as large as an egg : it was quickly saturated with the 
liquid and at once put in the tunnel. 
The experiments were carried out from 4*30 P- M. dark and 
from daylight to 9 or 9.30 A. M. These, as I afterwards learned 
from the owners of the fields, were not good hours as the rats 
were then for the most part out in the field. They are all in their 
burrows from 10 a. m. to 4 p . M. and as this is the proper time to 
apply carbon bisulphide, I did not do so as I had the liquid in 
a tin, and did not care to risk a metal vessel to a continuously 
