SENNA. 
201 
The glucoside acid, that now is known to confer on senna its purgative pro¬ 
perty, has been named by its discoverers Cathartic acid. Its formula has been 
stated as C 180 H 96 N 2 SO 82 , which, if true, accounts for its extreme instability. 
It is insoluble in water, strong alcohol, and ether, but enters readily into watery 
solution when combined with alkaline and earthy bases. Its ammonia salts give 
brownish flocculent precipitates with salts of silver, tin, mercury, copper, and 
lead. Antimonial salts, tannin, yellow and red prussiates, have no effect upon 
it. Alkalies, aided by heat, act destructively upon it; boiled with a mineral 
acid it splits into a peculiar kind of glucose and an acid that has been named 
Cathartogenic. Its formula is said to be C 132 H 58 N 2 S0 44 . Cathartic acid, in 
a combined state and of tolerable purity, is prepared by partially precipitating 
by strong spirit a watery infusion of senna, concentrated to a syrupy state by 
evaporation in vacuo. The filtrate is now treated with a much larger bulk of 
absolute alcohol, and the precipitate thus obtained is purified by repeated solu¬ 
tion in water and precipitation by alcohol. 
To obtain the pure acid, advantage is taken of its colloidal properties; the 
crude cathartate is dissolved in moderately strong hydrochloric acid, and sub¬ 
jected to dialysis on a diaphragm of parchment paper. The minimum dose of 
this pure acid was found to be about grains, which caused several stools with 
decided griping. 
The combinations of cathartic acid that I have made are, the cathartate of 
ammonia, prepared from cathartate of lead by my original process, and the mixed 
cathartates, prepared according to Dragendorf’s method as modified by myself. 
Of the former nearly pure salt, I have fouhd 3f grains to purge fairly as to 
amount, but slowly as to time, and with considerable griping. Of the latter, 1\ 
grains purged violently with much griping and sickness, which continued through 
the greater part of the day, completely knocking the patient out of time; 4 
grains would, I think, be a fair dose. It should, however, be given in conjunc¬ 
tion with a saline and an aromatic corrective of some kind. With phosphate 
or potassio-tartrate of soda an agreeable and effective aperient might be formed ; 
possibly the cathartate itself might be modified in its action by opium, bella¬ 
donna, or hyoscyamus. I cannot affirm, however, that the active principle has 
a more unpleasant action than the raw drug, but such I should expect to be the 
case. 
It obviously would be improper to combine senna with any of its metallic 
precipitants should such be desired, which is not likely. It is here satisfactory 
to observe that the cathartate of magnesia is soluble, and that the old-fashioned 
black draught agrees with new-fashioned science. 
The effect of acids on senna must not be overlooked. The mineral acids pre¬ 
cipitate, aided by heat the}’- destroy, its active principle, as I have pointed out 
already. The organic acids precipitate it from its aqueous solution, but do not 
decompose it on boiling. Here then is a very important distinction, one that 
saves the credit of such preparations as the old Infusum Sennse Limoniatum, De- 
coctum Tamarindorum cum Senna, and others of the class, not forgetting the 
much used Conf. Sennse Co. 
The long-continued action of heat on cathartates exposed to the air in watery 
solution, is to decompose them, rendering them inert. Decoctions and extracts 
of senna are therefore to be made with proper precautions, or preferably aban¬ 
doned in favour of the recent and quickly-made infusion. 
Fermentation either of the infusion, pure and simple, or of the infusion made 
into syrup with sugar, decomposes the glucoside most completely. I have been 
assured by a constant taker of Ess. Sennse Dulc., that the latter part of the 
bottle of essence is never so active as the first. Particular care, therefore, 
should be taken to obviate fermentation. The best way to do so is to add to 
each fluid ounce of syrup two minims of chloroform dissolved in a little alcohol. 
VOL. x. . p 
