416 
REPORT OP CHEMICAL LABORATORY 
OrICtIN of (tUAI A\D the CoXniTIONrt affecting its I’roiiuction 
Origin of gum 
Conditions 
affecting its 
production 
Soil 
Analyses of 
soils from gum 
districts 
It must be borne in mind that the remarks below refer solely to the “hashab" tree. 
Even a superficial examination of the subject is sufficient to show clearly that, as regards 
gum production, every variety of tree is a law unto itself. This is readily explicable 
on the microlhc theory of gum formation, since it is to he expected that different 
organisations should vary as to their ability to resist the attack of the microhe. 
Soil. One of the conditions which have been noted by Muriel as apparently favourable 
to the production of gum is a ferruginous, sandy soil. Several samples of soil from Kordofan 
gum gardens have been collected and examined. It may be noted that, while reddish from 
the presence of iron, the actual amount present is nevertheless not so great as in most Sudan 
soils. The practical absence of organic matter renders such iron as is present more evident. 
Analyses of several of these soils were made. The following two were collected l)y 
Mr. A. F. Broun, Director of Woods and Forests. One was from a good gum-yielding 
geneiua, and the other was apparently similar soil where hashah trees were absent. 
Laboratory unmlier 
549 
O.50 
Description 
Soil from good 
hashab geneina 
Apparently similar soil. 
No hashab 
Loss at 10(1" C. 
0-094 
0-038 
Loss on ignition ... . 
0.08'2 
0-075 
Insolnlile in liydrocliloric .acid . 
97-97 
9.8-54 
Carbonates (exjires.sed as CaCO„) ... 
O-0-38 
0-019 
Nitrogen 
0-046 
0-041 
Snhihle in huiUny /ii/di'ocliloric iiai/ 
Ferric oxide (Fe.^O.,) . 
0-60 
0-47 
Phosphates (P.^D,-,) . 
0-012 
0-011 
Potashi^KoO) 
0-052 
0-048 
Both of these are obviously extremely poor — what would usually be described as barren, 
sandy soils. The sample taken from the point where no hashah was found is slightly poorer, 
but the difference between the two is so slight that one must evidently look elsewhere for the 
cause of the absence of hashab growth. 
The following are more complete results of examination of two samples of soil from a 
"ood geneina (that of Ali Nur-ed-Din) near Taiara. The first was taken from the surface 
and the second from a depth of about 10 feet. At the time of collection the deejier soil 
looked darker, Init this was found to lie due simply to moisture, .\fter standing in the air 
both were of the same appearance—lightly red and sandy. 
For the mechanical analyses the method described by H. D. Ilalh was employed. 
Joiirnif/ of the Chctuical ^Socirf//, 19(U, p. OdI). 
