444 
KErOKT OF CHEMICAL LALOUATOKY 
Specific 
rotation 
Hashab 
The following table shows the principal results, the temperature at the time of 
observation being 34“ C. ;— 
Source of Gum 
Rotation of a 10% solution 
in a 100 mm. tube 
Rotation of a 10% solution in a 
100 mm. tube after hydroij'sis 
30 middle-sized trees, 1st colleetiou ... 
- 3-01“ 
4 - 5-48° 
„ „ >. . 
- 3-00 
-b 5‘4;) 
„ 3id „ . 
- 2-95 
-1- 0*45 
,. „ -till „ . 
- 2-89 
4- 5-40 
„ „ ">tl> >, . 
- 2-81 
4 - 5-48 
„ „ (itli .. 
- 2-89 
4- 5-48 
3U small trees, 1st eollecdion, hard portion . 
- 3-13 
4- 5-42 
„ ,, ‘lud „ hard „ . 
- 3-14 
4- 5-48 
j) )) 2 ik1 ,, soft ,, ... ... 
- 2-93 
4- 5-42 
,, ., 3rd „ hard „ 
- 3-03 
4- 5-49 
„ „ 3rd ,, soft. „ . 
- 2-9.5 
4 5-43 
„ „ 4th „ soft „ . 
- 2-85 
+ a‘50 
„ oth „ soft ,, 
- 2-98 
+ 5-47 
,, „ Oth ,, soft. ,, 
- 3-07 
-1- 5-58 
30 large trees, ‘iiid collection, hard portion . 
- 2-94 
4- 5-38 
„ „ 2nd „ soft .. . 
- 3-02 
4- 5-.5.5 
„ „ 5th „ hard .. . 
- 2-77 
4- 5‘35 
., ., oth „ soft. „ . 
- 2-89 
4- n’oO 
Kordofan gum, hard and strong ... . 
- 3-()U 
4- 5‘30 
„ „ “ bleached " sample . . 
- 2-88 
4- 5-38 
„ „ giving a roiiy solution . 
- 2-91 
4- 5-40 
,, ,, December, 1907 
- 3-11 
4- 5.35 
Gedaref gum, .lauuary, 1908 . 
- 3-09 
4- 5-33 
Scucgal gum, tjrossc hlanchc ... 
- 2-84 
4 - 5-48 
,, ,, pci lie blanche 
- 2-70 
4- 5-48 
„ „ bus dti flr.uvc, 1908 . 
- 2-93 
4- 5-42 
The gum from the small, middle-sized and large trees in the above table came from 
Ali Niir-ed-Din’s garden, and is the same as that described in greater detail by Dr. Beam. 
This table of optical activities is of great interest in that it indicates a constant specific 
rotation for llashab gum, not only in aqueous solution, but also after hydrolysis with 
sulphuric acid. In a few of the collections the gum had been divided into two portions, one 
consisting of the soft friable gum, and the other being composed of the hard glassy tears. 
We thus have gum from trees of very different sizes, and, probably, these differed in age 
correspondingly. The season during which the gum from these trees was collected was 
from the middle of January until the exudation of gum stopped, none unfortunately Ijeing 
gathered in November or December. 
