RF.rORT OF CHEMICAL LABORATORY 
435 
TaI,H (tUM 
Talh gum is collected from two varieties of Acacia seijal, one known locally as 
“ falha haini-a," or red talh, and the other (.4. sei/al, var. fintula.) as lalha heida, or white 
talh. These trees are not tapped hy the gum collectors, who simply pick off such gum as 
exudes from accidental cracks or fissures in the bark. The crude gum of both varieties has 
apparently identical qualities. It is inferior to hashab gum, but finds a ready sale at a 
lower price. 
Talh gum as found in the market is in small pieces or fine powder, the gum being 
exceeding friable and the tears falling to powder during transport. It consists of a mixture 
of various coloured particles, ranging from absolutely colourless through shades of yellow 
and brown up to dark red. It is frequently more acid than the gum from .1. rcrck, and 
sometimes possesses a distinctly sour taste. Its solution is usually fairly dark, becoming 
much more so on exposure to the air. 
Twelve samples of talh gum from Kassala district were examined witli the following 
results: — 
Minimum 
Maximum 
Average 
Acidity (equiv. to milligrams KHO) . ... . 
2-75 
6-29 
3-7C, 
-Ash, per cent. 
2'4-2 
4-42 
2-97 
Viscosity of f Degrees of retardation 
20*2 
4.3-0 
36-.3 
•20 per cent.K 
solution [Sugar equivalent, grammes per 100 c.c. of solution 
61-.3 
6.3-8 
02-G 
All yielded coloured solutions which became much darker on exposure to the air and 
had a more or less pronounced sour taste. 
By selecting only the colourless pieces a very marked improvement was noted. Thus — 
Minimum 
Maximum 
Average 
Acidity (equivalent to milligrams KHO) 
2-80 
3'ori 
.3-13 
Ash, per cent. . 
2-67 
2-89 
2-81 
Viscosity of f Degrees of retardation 
29-2 
.34-1 
31-6 
20 per cent. < 
solution [ Sugar equivalent (grammes per 100 c.c. of solution) ... 
61'3 
G2'3 
61-6 
The solutions were in all cases free from sour or other marked taste and practicallj' 
colourless, with little or no tendency to darken on exposure to air. 
An experimental tapping of red talh trees was carried out at our request by 
S. A. Wood, Inspector in the Woods and Forests Department. The result was a 
greatly increased yield and a very decided improvement in quality, especially as regards 
the colour of the gum, its taste, acidity, and the absence of darkening of the solution on 
exposure to the air. Experiments are about to be undertaken in order to determine the best 
method of tapping, since under some conditions the gum exudes in such large masses that, 
apparently, fermentation, attended by coloration and increased acidity, is the result. 
The following are the results of examination of a sample of good gum obtained by 
tapping and a comparison with the ordinary gum collected in the same district (Sennar) 
from untapped trees. 
Talh glim 
from Acacia 
seyal 
Form of Talh 
gum 
Analysis of 
Talh gum 
Analysis of 
selected 
Talh gum 
