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TRANSACTIONS OF THE SECTIONS. 
On the Resin of Sarcocolla. By Professor Jounston. 
The resin of sarcocolla of commerce is separated, by water, into three 
portions. 
1. A gum A, which does not dissolve in water or alcohol, but which 
is in a great measure washed out by means of the former solvent. 
2. A portion B, insoluble in water, but soluble in alcohol, which is 
of a resinous aspect, and is represented by Cy H5. O,4 
The hydrate is C,, H;, O,, + 2 HO when dried at 60°. 
This portion B is separated (decomposed?) by bases into two or 
more organic compounds, the alcoholic solution giving, with neutral 
acetate of lead, a salt containing an organic constituent represented by 
C4o Hos Oro 
Ammonia throws down from the mixed solutions a second salt of 
lead, the constitution of which has not yet been determined. 
3. The portion taken up by water from the crude sarcocolla when 
evaporated to dryness, is separated by alcohol or ether into a solu- 
ble (C), and an insoluble portion D. 
4. The soluble C, dried at 212°, gives discordant results, approach- 
ing to C4) H;. O,,, but when treated with bases, gives salts containing 
organic constituents of a different constitution. 
A neutral acetate of lead throws down a salt represented by 
Pb O + C,, H,; O;,; and the subsequent addition of the neutral ério 
acetate, a salt represented by 2 Pb O + Cyo Hyo Oye. 
5. The portion D, insoluble in alcohol, but soluble in water, consists 
of a gum, and of a substance which is precipitated by neutral acetate 
of lead in curdy flocks. 
The investigation is still in progress, and the results are to be con- 
sidered as open to correction. 
On some Varieties of Peat. By Professor JouNSTON. 
The author exhibited some varieties of peat from the Moss near 
Paisley, which he stated were illustrative of a transition from the 
comparatively fresh vegetable matter to a substance resembling coal, 
but which he affirmed to be ulmic acid. The author stated that the 
same substance might be obtained from peat by digesting it in ammo- 
nia, and afterwards precipitating the brown solution by an acid; while 
on the other hand, caustic potash extracts another, and which he pro- 
posed to term humic acid. 
On a Mode of Detecting Minute Portions of Arsenic. By Dr. CLARK, 
of Marischal College, Aberdeen. 
This mode has been applied by the author to the detection of arsenic 
in commercial specimens of the metals, tin and zinc. Grain tin, made 
in Cornwall, contains arsenic, which seems to be the occasion of the 
peculiar smell of the hydrogen evolved from that metal by the action 
G2 
