642 
ON AFRICAN TRAGACANTH. 
the adhesiveness of pilular masses I find the former, whether in the form of powder 
or mucilage, as advantageous as ordinary tragacanth. 
The fine powder on exposure for some days to a temperature of 212° F. 
loses 20-50 per cent, of its weight. The formula C 12 H 22 0 u -|- 5H 2 0 would 
exactly require 20’5 per cent, of water. It is not soluble in an ammoniacal 
solution of peroxide of copper; repeatedly boiled with fuming nitric acid 
it affords an abundance of mucic acid. 
The weight of the powder as obtained by drying it at 212° F. does not 
diminish at 230° F. (110° C.). Upon incineration, the dried powder leaves 7‘8 
per cent, of ash of which the prevailing constituent is carbonate of calcium; 
0T22 gramme of the ash indeed contain (after having been previously moistened 
with a solution of carbonate of ammonium and again gently heated, in order to 
prevent any loss of carbonic acid) 0-0587 gramme carbonic acid. The amount 
of the basic part of the ash is accordingly 4-08, referring to 100 parts of the 
above powder. 
The dried and powdered gum was now submitted to elementary analysis* by 
means of peroxide of copper and a current of oxygen. 
Carbonic Acid. Water. 
I. In the first experiment 0*3412 gramme yielded 0*5066 and 0-1648 
II. „ second „ 0*2982 ,, „ 0-4380 „ 0-1524 
that is to say 
I. 0-1374 of carbon and 0-01831 of hydrogen 
II. 0-1195 „ „ 0-01693 „ „ 
accordingly the percentage is in . . I. II. 
Carbon. 40-27 40-06 
Hydrogen. 537 5-91 
These numbers however, referring to the crude tragacanth, must be calculated 
with regard to the fact, that 100 parts of the raw drug correspond to 95 92 
parts only of pure tragacanth, if we deduct the above 4 - 08 per cent, of the 
bases contained in the ash. 
Thus then the percentage-amounts are for . . I. II. 
Carbon. 41 98 41-76 
Hydrogen. 5 59 5 91 
The formula of gum arable shows the following numbers : 
12 C . . . 144 . . . 42-12 
22 H . . . 22 . . . 6-41 
11 O . . . 176 . . . 51-47 
342 100-00 
Common tragacanth and other similar gums however are usually referred to 
the formula 
12 C . 
. . 144 . . 
. 44-44 
20 H . 
. . 20 . . 
. 6-17 
10 O . 
. . 160 . . 
. 49-39 
324 
100-00 
I restrict myself for the moment to the mere communication of the above facts 
* Performed in my laboratory by Dr. Krausbaar. 
