SENNA. 
199 
I found it to consist of phosphate and sulphate of lime combined with resinous 
acids, some of which were soluble in alcohol, some in ether, some only in alka¬ 
line solutions. The whole treated with liquor potassse in considerable excess, 
dissolved, producing a rich brown colour. From the filtered solution hydro¬ 
chloric acid precipitated the resins,—brown in colour when pulverulent, black 
when fused into masses. Eight grains of this substance taken for a dose pro¬ 
duced no effect whatever on the bowels. As similar resinous acids were not pre- 
cipitable from liquor sennse by acids in the cold, I at once suspected that they 
derived their origin from the slow decomposition of an unstable glucoside. An¬ 
other supposition that they were products of oxidation was negatived by the 
fact, that the precipitation occurred in perfectly closed vessels. An examination 
of liquor sennse presented the following reactions:—It was acid to test-paper. 
When treated in the cold with weak hydrochloric acid it did not deposit anything 
material before ten or twelve hours had elapsed. Boiled with any mineral acid 
it deposited a considerable amount of dark resin, leaving the fluid nearly colour¬ 
less. Comparative tests before and after boiling with acid, with Fehling’s liquor 
showed that the proportion of glucose had been increased by that treatment. 
Neutral acetate of lead threw down an abundant pale precipitate. No precipi¬ 
tate of consequence was obtained by using either tannin, ammonia, or iodo- 
hydrargyrate of potash. Basic acetate of lead applied to the filtrate from the 
neutral acetate, produced an abundant orange precipitate, leaving the liquid to 
all appearance destitute of any active principle of senna. This lead precipitate, 
treated with cold dilute sulphuric acid, yielded a dark solution, that when boiled 
with a mineral acid yielded a resinous precipitate, and a disagreeable smell of 
stale senna. The lead was therefore in combination with the glucoside, for 
which I was in search. Guided by these results, my experiments were resumed 
on a larger scale. 
A quart of Liquor Sennse that within a fortnight of its preparation had com¬ 
menced to deposit resin, was neutralized with ammonia. The precipitate ob¬ 
tained consisted mainly of phosphate of lime. 
Neutral acetate of lead being added in excess to the filtrate a precipitate was 
obtained, consisting of certain organic acids in combination with oxide of lead. 
This precipitate washed, suspended in water, and decomposed by sulphuretted 
hydrogen furnished a brown acidulous liquid, which was decolorized to some ex¬ 
tent by animal charcoal, and then neutralized with baryta water. Of the baryta 
compounds one part was soluble, the other not. The insoluble part was treated 
with sulphuric acid, which eliminated the organic acid. The soluble part was 
reprecipitated with acetate of lead, and decomposed with sulphuretted hydrogen. 
The acids thus obtained were compared in their reactions with the better known 
organic acids, but could not be identified. 
As I was unable to devote to the subject sufficient time for complete exami¬ 
nation, and the results were not likely to be of pharmaceutical interest, I handed 
it over to Dr. Attfield, with a request that he would put one of his senior pupils 
upon it, if he thought the subject worth following up. I thought it not un¬ 
likely that the inquiry might result in filling up some gap in a homologous 
series, and thus be of scientific interest. I understand that the subject is in the 
hands of the senior Bell Scholar. 
The addition of diacetate of lead to filtrate No. 2, produced a copious orange 
precipitate, which, when washed and diffused through water, was decomposed 
with sulphuretted hydrogen. The brown acid liquid that resulted was warmed, 
neutralized with ammonia and evaporated to dryness; redissolved in water, 
spirit of wine was added till a precipitate began to form. This precipitate con¬ 
sisted of sulphate of ammonia, in small quantity. The liquid poured off from 
this was treated with a larger dose of spirit, when the greater part of the glu- 
coside acid, combined with ammonia, fell to the bottom in a treacly mass. This 
