ON AFRICAN TRAGACANTH. 
641 
The thanks of the Meeting were also accorded to several wholesale houses and others, 
for seasonable contributions and promises of assistance in the formation of the Museum 
and Library. 
The first course of lectures on Inorganic Chemistry, by Mr. G. Harrison, being nearly 
completed, a course on Materia Medica, by Mr. G. R. Gowlaud, was announced. The 
introductory lecture to be given before the Society on the 12th of May. A Botany 
Class is also in course of formation. A number of new Members, Honorary Members, 
and Associates having been proposed, the meeting separated. 
SUNDERLAND CHEMISTS’ ASSOCIATION. 
The Second Meeting of the above society was held on Wednesday evening, 14th 
April, when W. Thompson, Esq. (Mayor), was unanimously elected President, and a 
sub-committee consisting of Messrs. Dobinson, Sharpe, Harrison, Dalby, and Bird, were 
appointed, to assist in carrying out the objects of the society. 
It was resolved that, by the next meeting the committee should be prepared with a 
code of rules for governing the society, and endeavour, at as early a period as possible, 
to arrange a list of prices, for dispensing and retail, that will meet the views of all the 
members. 
ORIGINAL AND EXTRACTED ARTICLES. 
ON AURIC AN TRAGACANTH. 
BY DR. F. A. FLUCKIGER, OF BERN. 
The substance to which I here apply the name of African Tragacanth is an 
exudation from the trunk of Sterculia Tragacantha Lindl., a tree of moderate 
size occurring in Tropical Western Africa from Senegambia to Congo. Muci¬ 
laginous matter is known to characterize several plants of the order Sterculiacece, 
in which respect one of the most noteworthy is Sterculia urens Roxb., an East 
Indian tree which exudes abundantly a substance resembling tragacanth. The 
exudation of the African species under notice has also long been known ; but as 
its chemical nature has not hitherto been investigated, I think the following ob¬ 
servations may be of interest. The specimen examined is authentic, having been 
collected with the plant by the late Mr. Barter, and transmitted to the Royal 
Gardens of Kew. 
African Tragacanth, as I have received it, consists of irregular, knobby, un¬ 
dulated, droppy, or stalactitic masses, more or less bubbly or cavernous, often 
exceeding an ounce in weight, of a pale yellowish hue or almost colourless, in 
small fragments nearly transparent, but seen in mass somewhat opaque by 
reason of innumerable cracks, which also render it much more brittle than true 
tragacanth. Each mass is in fact traversed by curved fissures answering to 
successive protrusions of gum. Fragments of bark are often adherent to the 
fiat or inner side of the pieces. 
With 20 parts of water, coarsely powdered African tragacanth forms, like 
common tragacanth, a thick tasteless jelly ; with 40 parts of water, the jelly be¬ 
comes more fluid. Only a very small quantity of gum is really dissolved in the 
water; the filtered liquid is not precipitated either by neutral acetate of lead or 
by absolute alcohol, but on addition of basic acetate of lead it becomes a little 
turbid. The jelly itself reddens litmus paper. Neither thin slices of the dry tra¬ 
gacanth nor the jelly exhibit any trace of cellular structure or of starch, even when 
examined in polarized light by means of the microscope. In this respect the tra¬ 
gacanth of Sterculia differs from that of Astragalus. As a means of promoting 
