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BRITISH PHARMACEUTICAL CONFERENCE. 
Argel. As the latter are now known to be destitute of purgative power, and 
purely bitter, it would be interesting to ascertain the comparative potencies of 
pure senna, and of that mixed with cynanchum. Should it turn out that the 
admixture really effects an improvement of quality, we may perhaps, without 
great stretch of charity, ascribe the systematic admixture of the two leaves to 
a desire to improve the article. Cheapen it, it does not. It has been remarked 
with wonder by travellers, that the senna leaves are quite as easily obtainable 
as those of the plant used presumably for its sophistication. 
Senna was invariably exhibited in a watery vehicle, and this is as it should 
be ; strong spirit fails altogether to extract its active principle, notwithstanding 
Christison’s statement to the contrary. 
Among the more noteworthy examinations of senna of recent date are those 
of Robert Rau, of Bethlehem, Pennsylvania, and of Professor Dragendorf and 
Herr Kubly, of Dorpat. 
Rau’s results have since been disproved, but as his experiments present many 
points of interest I will shortly enumerate them. The paper will be found in 
extenso in the ‘American Journal of Pharmacy’ for 1866. He commences by 
asserting the inertness of the resin extracted from senna by the use of alcohol, 
and in that is perfectly correct. 
The active principle being supposed still to remain in the residue of the ope¬ 
ration, the senna is extracted next with cold water, and to the infusion diacetate 
of lead is added in excess. The filtrate from the precipitate thus formed is 
freed from lead by sulphuric acid, and being then evaporated, the sweet ex¬ 
tract was found destitute of purgative action. He found the same inertness 
in that part of the extract soluble in spirit—the so-called cathartin of Lassaigne. 
The yellow lead precipitate was next examined. When dried and boiled with 
alcohol it yielded a substance of a deep yellow colour which was darkened by 
alkalies. It consisted of two resinous bodies, chrysoretin, etc. The residue 
suspended in water was decomposed with sulphuretted hydrogen, and furnished 
only a u tasteless , gummy substance of acid reaction ,” that seemed unworthy of 
further notice. 
The dried sulphide boiled in alcohol yielded a resinous, very nauseous sub¬ 
stance insoluble in water, soluble in alcohol and in ether. 
The dried sulphide boiled in ether gave a crop of interlaced acicular crystals 
of dirty white colour, at first tasteless, afterwards persistently bitter and 
nauseous. Five grains purged actively five hours after taking. A second 
quantity of crystals was obtained from the liquid by treatment with animal 
charcoal, and boiling as before in ether. He claims for this substance the 
position so long usurped by the pretended senna Cathartin of Lassaigne and 
Fenuelle, and names it “ Sennin.” 
The characteristics of this new “ Sennin ” are thus described :—It is insoluble 
in water, cold or hot, insoluble in acids, insoluble in alkalies, insoluble in cold 
alcohol; soluble, to some extent, in hot alcohol and in ether, but especially 
soluble in chloroform. All this being true, how on earth could the sennin have 
been induced to leave its nidus by the mere action of cold water? This con¬ 
sideration determined me on repeating the experiment, but fortunately I was 
saved the trouble by the announcement of Herr Kubly, who had carefully trod¬ 
den the same path as Mr. Rau, but with greater discernment, that the “ dirty- 
white interlaced acicular crystals ” were in point of fact neither more nor less 
than sulphur. It must, however, be remembered to Mr. Rau’s credit, that be 
gave the finishing blow to the pretensions of Lassaigne’s Cathartin, and also 
proved the incorrectness of Martius’ assertion respecting chrysophanic acid,—it 
exists in senna in very minute proportion only. 
My own experiments were commenced in 1862, by an examination of the pre¬ 
cipitate that so invariably collects at the bottom of old samples of Liquor Sennse. 
