Observations on Squamosis and Exanthema of the Citrus. 1 2 3 
QUALITATIVE REACTIONS OF PRUNUS AND CITRUS GUMS. 
Reagent. 
Lemon gum . 
Cherry gum. 
Plufti gum. 
Hydrochloric acid and ) 
phloroglucin ) 
Alcohol 95 per cent, excess 
Acetic acid, dil. .... 
Glacial acetic acid, excess 
Nitric acid 
„ „ and ammonia j 
Millon’s reagent . . . 
Tannic and acetic acids . 
Sodium molybdate . . . 
Potassium-mercuric iodide 
Phosphotungsticandsul- ) 
phuric acids \ 
Sodium phosphomolybdate 
Sodium phosphotungstate 
Mercuric nitrate and ni- ) 
trie acid j 
Adamkiewicz reaction 
Biuret test 
Lead acetate and sodium ) 
hydrate $ 
Hydrochloric acid . . j 
Ferric chloride .... 
Fehling solution . . . 
Lead acetate ..... 
Ammoniacal lead acetate 
Basic lead acetate . . . 
Calcium hydrate . . . 
Potassium hydrate . . . 
Sodium hydrate .... 
Barium hydrate . . . j 
Aluminium hydrate . . j 
Sodium borate .... 
Copper sulphate . . . j 
bright red, then dark pp. 
white pp. 
bright red, then dark pp. 
white curdy pp. 
bright red, then dark pp. 
white pp. 
white pp. 
solution coloured yellow 
colour heightened 
solution deep red 
white pp. 
solution coloured yellow 
colour slightly 
heightened 
solution yellowish 
yellow pp. 
white pp. 
solution coloured yellow 
colour heightened 
solution reddened 
cloudy white pp. 
large curdy pp. 
solution thickened 
white pp. 
liquid cloudy 
fine pp. remaining in 
suspension 
trace of reaction 
fine pp. remaining in 
suspension 
bright yellow, then 
clear amber 
red gelatinous pp. 
bright yellow, then 
dark brown 
bright yellow then dark 
brown, slight pp. 
reaction doubtful 
milky 
abundant gelatinous pp. 
fine gelatinous pp. 
milky, slight pp. 
abundantgelatinous pp. 
fine curdy pp. 
abundant gelatinous pp. 
sol. slightly thickened 
sol. thickened 
very slight fine pp. 
remaining in sol. as 
a faint cloud 
sol. thickened, slight 
indefinite pp. 
sol. thickened 
sol. thickened 
very slight fine pp. 
remaining in sol. as 
a faint cloud, 
sol. thickened, faint 
cloud 
sol. thickened 
very slight fine pp. 
remaining in suspension 
sol. thickened 
very slight fine pp. 
remaining in sol. as 
a faint cloud 
sol. thickened, faint 
cloud 
sol. thickened 
The gums of Prunus and Citrus I have found to be soluble in water. 
A 6 per cent, solution of cherry gum is very thick, but the gum dissolves 
with shaking within twelve hours at this concentration. The lemon and 
plum gums dissolve much more readily than the cherry gum, and at the same 
concentration as the latter form a less viscous solution. All the gums 
contain nitrogenous matter, probably in variable amount. 
4. Technique. 
In our study of the gums of Prunus and Citrus we found that they 
are soluble in water, from which they are precipitated out by strong alcohol, 
or an excess of glacial acetic acid. In preserving material for examination 
it was, therefore, quite evident that alcohol and acetic acid mixtures, or 
