245 
1916-17.] On some Nuclei of Cloudy Condensation. 
ing to that in liquids. In liquids these fine particles remain for a 
long time in suspension, though Graham, who first studied them, regarded 
them as unstable. 
Small particles in liquids keep separate from each other, while in gases 
they tend to coalesce — a difference in behaviour which is very important. 
By this action the very small particles in air tend to diminish in numbers 
but to grow in size. Nature seems to have no use for these extremely 
small particles till they are aggregated and grown large enough to 
become cloud particles with the slightest supersaturation. These ex- 
periments seem to indicate that what are now called large ions are 
nothing more than very small solid or liquid particles with an ion or 
ions attached. 
(Issued separately June 28 , 1917 .) 
