MALARIA EXPEDITION TO NIGERIA 253 
no fever prevails, led us to try the action of the native potash as a ' culicicide.' 
Native potash is a substance occurring in large quantities as an efflorescence in the 
country referred to, and to its action of rendering water, in which the potash is 
dissolved, distasteful to Anopheles, is ascribed the freedom of the district from 
mosquitoes. From our experiments we are unable to infer any decided culicicidal 
effects (its action was much inferior to that of lime) ; we are, therefore, inclined to 
consider the freedom of the district from mosquitoes, if it be really so, as not due 
to the presence of this substance. 
s 
