44 BOTANICAL GAZETTE [yoLy 
oxygen carrier. MAvYER (10) also attributes the beneficial effects 
of the alkali salts to the fact that they are easily reduced. BArTH © 
(1) suggests that the salts may have a beneficial action by raising 
the temperature of the leaf; he also attributes the harmful effect 
of the chlorides to the fact that they fuse and coat over the material, 
thereby preventing complete combustion. 
Object 
The object of this work is to study the effects of various salts 
closely related to the salts of potassium with a view to obtaining 
some light upon the conflicting theories. It has been suggested 
that the effect of the various salts upon the colloidal state of the 
material of the leaf may bear some relation to the problem. It 
was thought that probably potassium possesses some peculiar 
_ chemical properties which may account for its action. 
ses of salts upon combustion of tobacco 
METHOD 
‘The method of experimentation consisted of treating leaves and 
filter paper with various salts and noting their effect upon the 
__ fire-holding capacity. The samples of tobacco used in this work 
a Jeete OF 8 sine brain, of a tear Hiden pe oe tobacco grown in 
oe under definite fertilizer treatments. The leaves 
y had been well sweated. In all cases the solutions of 
Ej rapoadiess were 28.9 per cent normal. In order to see 
__whether the effect of the salts was upon the colloidal state of the 
oe Rioiee by a treatment with o.2 no 
ue materials of the leaf, some of the leaves were rendered acid by 
_ treatment with o.5 normal acetic acid, and others were rendered : 
