EED-SQUILL POWDERS AS RATICIDES 
19 
EFFECT OF TEMPERATURE ON TOXICITY 
Powders made at 80° to 100° C. were more toxic than those made 
at other temperatures. Apparently they were more toxic than the 
fresh bulbs used in their manufacture, even after an 80 per cent 
allowance had been made for the moisture content of the bulbs. 
The powders made at room temperature (25° C.) and at 60° C. were 
less toxic than the fresh bulbs (on a dry basis), and also less toxic 
than powders made at 80° C. ^ Temperatures above 100° C. seemed 
to decompose the active principle. Somewhat similar findings have 
been reported by Claremont (5). Although heating rarely increases 
toxicity, such a result is not unknown, as in the conversion of quinine 
into quino toxin. Further investigation is necessary to determine the 
factors underlying this apparent increase in toxicity. 
It was concluded that the most toxic powders were produced at a 
drying temperature of 80° to 100° C. (Table 6.) 
Table 6. — Effect of temperature on toxicity of red-squill powders 
[Mg. per kgm. of body weight] 
Series Noj 
Equiv- 
alent 
mini- 
mum 
lethal 
dose of 
undried 
fresh 
bulb 
Minimum lethal dose of squill dried at — 
25° C. 
60° C. 
80° C. 
100° C. 
110° C. 
120° C. 
140° C. 
1 (hot-air oven). 
750 
1, 500 
400 
1,000 
750 
500 
2 (hot-air oven). 
1,250 
1, 250 
750 
2,000 
1, 500+ 
750 
2,500+ 
750 
3, 000+ 
750 
750 
3 (vacuum oven). 
2,000 
4 (electric oven) 
1, 250 
1, 250 
DIRECT OVEN DRYING VERSUS PRELIMINARY AIR DRYING 
^ One portion of each of seven pairs of samples prepared from the same 
composite lots of squill bulbs was weighed and placed directly in the 
drying oven at the desired temperature. The other portions were 
exposed on open watch glasses in the air for five days, after which they 
were dried at the same temperatures as the first set. (Table 7.) 
Table 7. — Effect of type of drying on toxicity 
f Sample No. 
Minimum lethal dose 
of squill powder — 
Sample No. 
Minimum lethal dose 
of squill powder- 
Direct 
oven dried 
Prelimi- 
nary air 
dried 
Direct 
oven dried 
Prelimi- 
nary air 
dried 
P. C. 719 
Mg. per kg. 
of body 
weight 
1,000 
250 
350 
500+ 
Mg. per kg. 
of body 
weight 
625 
250 
400 
350 
P. C. 723 
Mg. per kg. 
of body 
weight 
1,000+ 
500 
500 
Mg. per kg. 
of body 
weight 
500 
750 
625 
P. C. 720 
P. C. 724 
P. C. 721 
P. C. 725 
P. C. 722 
No difference was found in one set, but the variations in toxicity 
in the other sets suggested that other factors played more significant 
r61es in the development of toxicity. Direct oven drying is a simpler 
