THE PRESERVATION OF SYRUPUS FERRI IODIDI. 
365 
A cheaper, but far more troublesome plan is to infuse for two or three hours, 
in 2 gallons of boiling water, 1 lb. of senna, and to the filtrate add 1 oz. of ace¬ 
tate of lead ; to the liquor freed by filtration from the lead-precipitate add 8 oz. 
of liq. pi. diacet. Wash the yellow precipitate thus occasioned by decantation, 
and finally in a cloth, and then dry and powder it. It will weigh about 2| oz. 
Digest this powder with excess of recently-prepared sulphide of ammonium 
(NH 4 S), filter, and wash s. a. Evaporate the filtrate cautiously to a thin 
syrup, and add to it when cold four or five volumes of rectified spirit. The 
dried precipitate will be cathartate of ammonia tolerably pure, and will weigh 
about 3| drachms. The recovered spirit will be pure enough for general use, 
but comparatively little is required. 
Messrs. Smith will perceive that when using the term “ strong alcohol,” I did 
not refer to proof spirit. The first precipitate obtained by adding alcohol to a 
strong fluid extract of senna is mainly composed of malate or some other salt of 
lime. 
I should be very pleased if some one more fortunately placed than myself 
could be induced to test fairly the therapeutical properties of the active prin¬ 
ciple of senna. 
I am yours, etc., 
Weymouth, November 20, 1868. Thos. B. Groves. 
THE PRESERVATION OF SYRUPUS FERRI IODIDI. 
TO THE EDITOR OF THE PHARMACEUTICAL JOURNAL. 
Sir,—In the current number of the Pharmaceutical Journal I observed a 
letter u On the true method of keeping the Syrupus Ferri Iodidi free from 
changes,” in which your correspondent recommends the use of vegetable parch¬ 
ment as a covering to the bottles containing this syrup, instead of corks. In 
summing up the results of his experience he states that it would prove an addi¬ 
tional advantage if the syrup were made thicker than usual. I think the pro¬ 
priety of adopting this last recommendation is more than doubtful, for I have 
found that this syrup deposits crystals of sugar if made of greater density than 
the Pharmacopoeia directs ; that it is unnecessary, and that the trouble involved 
in capping with the vegetable parchment (a process which, I presume, would 
have to be repeated each time that a few drachms were removed) is unnecessary 
also, I proceed to show. 
I have in my possession a bottle of syrupus ferri iodidi which has now been 
made more than twelve months ; it is simply corked, and has been frequently 
exposed to the air. During the last six months the bottle has been kept only 
half full, and the syrup is still in perfect preservation. The method adopted to 
ensure this result is the simplest conceivable; it consists (as recommended in a 
previous letter, see April Journal this year) in exposing the syrup to sunlight 
for a short time daily. The bottle I have alluded to has been kept in a corner 
of the window of our shop, and has there been exposed to many changes of tem¬ 
perature. 
I believe I am indebted to a writer in the Pharmaceutical Journal for the 
method of preserving syrupus ferri iodidi by exposure to sunlight; possibly to 
the Messieurs T. and H. Smith, of Edinburgh, to whom pharmaceutists are 
under many obligations ; for I find on page 353, Vol. VII. second series, the 
following :—“ A few remarkable facts, in opposition to the general opinion that 
exposure to sunlight is conducive to generation of colour in such preparations, 
are, we think, worth relating. We have frequently observed that, under certain 
circumstances, coloured syrupus ferri iodidi is bleached by exposure to sunlight.” 
