54 BOTANICAL GAZETTE [JULY 
Summary 
1. The alkali carbonates of caesium, rubidium, ana potassium 
have a definite marked effect in promoting the fire-holding capacity 
of tobacco, which sodium and lithium carbonates do not exhibit, 
the order of effectiveness being as follows: caesium, rubidium, 
potassium. 
2. Of the oxalates tried, only potassium is effective. In the 
case of the carbonates and the oxalates in an alkaline medium, 
where lithium is more effective than sodium in the precipitation of 
colloids, it is slightly more effective also in promoting the fire- 
Iding capacity. In the case of the citrates there is no such 
relation and, in the case of the carbonates, potassium, rubidium, 
and caesium do not behave in this manner. It is doubtful, there- 
fore, whether the effect of the salts upon the colloidal state of the 
tobacco leaf is of any significance. 
3. Only potassium citrate is effective in promoting the burn. 
The citrates of sodium and lithium are nearly neutral in their effect. 
4. The organic salts of potassium, potassium carbonate, tri- 
potassium phosphate, di-potassium phosphate, and potassium sul- 
phate improve the fire-holding capacity; while potassium chloride, 
acid potassium sulphate, and mono-potassium gee ears are inju- 
rious to the burn. | 
Sodium 1 eh, eee a . yy : 2 4 at 
7S holding y slightly, — 
while all of the other sodium salts a are either neutral or injurious 
to the burn. 
ee The data obtained do not confirm the idea that the reduction 
_of the potassium salts will account for their favorable action. 
7. Data are given which indicate that the harmful action of 
: chases is nde $6 the fark Cat they fae ee 
oo Data are given which indicate oats the alternately giving 
___ offand taking up of carbon di 
effects of potassium carbonate. 
ae a bes of s € Si l oni : 
- Bs eric of the salts i in ‘raising the fe oa 
