138 
ItEPOBT OF CHBMIOAIi LAliOKATOKY 
Another sample of this gum, said to be from the same species of tree, was found to he 
in large irregular fragments, brownish black and almost opaque. It was not soluble in 
water, hut a mixture of about '2 per cent, formed with water a jelly-like mass. 
It does not seem likely that those two samples came from the same species of 
Coiiihret imi. 
STKHCULIA CINEHIA and STEHCULIA TOJIENTOSA 
Tartar gum 
from S/ereu/ia 
cineria and 
Da gum from 
SfercuHa 
tomentosa 
The t'oniier of these is known as Tartar (Ardh), and the latter Da or Kandi 
Both exude a gum apparently identical in character, and resemlding gum tragacanth rather 
than ordinary gum-arabic. On adding to water they do not dissolve to form a clear 
solution, hut swell up and form a stiff jelly. 
The gum from S. finii.eiit(}sii, obtained in Senegal, has in recent years come into use 
in the treatment of fabrics. 
The following are some results of examination of this gum, compared with a sample 
from Senegal. 
Laburatory No. 
.548 
542 
543 
Gum uf .. 
... 1 jS. tomentosa 
>S'. eincria 
S. tomentosa 
Source ... 
Bahr-ul-Ghazal 
Scniiar 
Senegal 
^Moiisturc 
1.5'2C per ceut. 
13T*2 per ccut. 
8 '‘JU per eeut. 
Ash 
. 7-05 „ „ 
5‘48 „ „ 
G-70 „ „ 
Acidity (c(iuiv. to milligrams KHO) 
. 13-7'J 
14-.511 
13-UU 
Two per cent, of these gums forms with water a colourless, slightly granular jelly. 
Another sample, from the frontier of Persia and India, behaved in a similar manner. 
DeTEKMIN ATION OF VlSCOStTY OF GuM Soi.UTIOK.S 
Determination 
of viscosity of 
gum sohili<jns 
Torsion 
viscosimeter 
Glass 
viscosimeters 
In the Second Eeport of these Laboratories attention was called to the application of the 
torsion viscosimeter to the testing of gum solutions and the methods of using the instrument 
were explained in detail. An experience of two more years, during which a very great 
number of tests w'ere made, confirms the favourable opinion which was formed at that 
time. The great advantage which it offers over glass forms of viscosimeters (in which the 
time of outflow througli a capillary tube or orifice is noted) is that the single instrument 
may he employed to determine with accuracy the viscosity at all concentrations, from the 
lowest up to the highest that it is possible to make. If glass flow instruments are employed 
and it is desired to make determinations at say 10, 20, and 30 jjer cent, concentrations, it 
will be necessary to have an instrument adjusted to each of these. A 20 per cent, solution 
