48 Improvements in Physical Science [Jan. 
his inaugural dissertation published at Keilin 1813. The following 
is an abstract of the results obtained. 
Sixteen ounces of the best bark were digested for three days in 
48 ounces of alcohol, of the specific gravity 0°819, being often 
agitated during that time. The aleohol was then poured off and 
45 additional ounces poured on the bark, and allowed to remain 
for two days. The bark powder, by this treatment, was so ex- 
hausted of soluble matter, that four pounds of water only formed 
with it an opal-coloured tasteless solution. The alcoholic tincture 
was distilled in a retort almost to the consistence .of a’syrup, 
and then mixed with 36 ounces of distilled water. There \preci- 
pitated a light brown powder, which, when well washed on the 
filter, became white ; but assumed a darker colour on drying. It 
weighed a half ounce and 40 grains. ° 
The filtered aqueous solution had a dark reddish brown colour, 
a very bitter and astringent taste; but was not sour, though it 
reddened litmus paper. It was mixed with a solution of pure car- 
bonate of potash. A precipitate of a light rose-red colour fell 
down. It weighed two drachms and 45 grains. ‘The liquid, 
which had assumed a darker colour, was saturated with sulphuric 
acid. ‘This occasioned the separation of a very bulky reddish- 
brown flocky precipitate, which only weighed 15 grains. It was 
insoluble in alcohol, but dissolved readily in water. ‘This solution, 
when mixed with sulphate of iron, became olive-green, and let 
fall a trifling precipitate. It was precipitated likewise by infusion 
of nutgalls and tartar emetic ; but not by solution of isinglass.. 
Of these precipitates, the first, obtained by mixing the distilled 
alcoholic tincture with water, is the substance which Gomes con- 
sidered as a new species of cinchonin. ‘The following experiments 
were made upon it. Three drachms and 40 grains were dissolved 
in alcohol of 0°820 specitic gravity; the solution was allowed to 
evaporate very slowly. Part of the substance fell down in the state 
of a reddish-brown precipitate. Another portion formed thin coats 
upon the sides of the vessel. These were transparent, and when 
light was viewed through them, assumed the appearance of a col- 
lection of needle-form crystals. ‘These coats possessed the follow- 
ing properties. 1. They-dissolved: readily in alcohol. 2. Boiling 
water dissolved about one sixth of its weight of them. 3. Caustic 
alkali readily dissolved them, and they were precipitated unaltered 
by the addition of sulphuric acid. 4. They were dissolved by con- 
centrated sulphuric acid, and precipitated of a darker colour by 
carbonate of potash. 5. They were insoluble in sulphuric ether. 
6..When put upon red-hot charcoal, they gave out an aromatic 
odour, and burnt with a light-coloured flame. 7. The tincture of 
nutgalls was not in the least altered by their solution in alcohol. 
They scarcely altered the solution of isinglass ; but sulphate of iron 
gave them astrong green colour, and occasioned a_ precipitate. 
‘The muriate of tin occasioned no change. Chlorine thrown into 
4 
