1010 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[June 15, 1872. 
a false rhubarb, and an examination of its structure was 
therefore made. 
The root was sawn transversely across, and the section 
smoothed with a knife ; it was then wiped lightly to 
remove the dust, and moistened with a few drops of 
water. Upon comparison then with a specimen of genuine 
Chinese rhubarb it was evident that it was obtained from 
a different source. 
The following are the principal points of difference 
between the French indigenous, the Russian and the 
Chinese rhubarbs :— 
French Indigenous Rhubarb .—A transverse section pre¬ 
sents a rayed aspect, formed of alternate white and red 
lines, proceeding from the centre to the circumference, 
the white lines being a little larger than the red. Just 
Fig. 1 . French Indigenous Rhubarb : transverse section, 
natural size. 
before reaching the circumference in circular pieces, or 
close to the edge in flat pieces, the radiating lines are 
cut by a brown zone, circular in the first, more or less 
interrupted in the second, but always visible. 
Russian Rhubarb .—The transverse section of this root 
exhibits yellow lines upon a white ground, distinct, some 
times anastomosing, long or short, sinuous, often broken 
by radial systems. These star-like forms are circular or 
lengthened, and of variable size ; their rays, clear yellow 
near the centre, become brown as they approach the cir¬ 
cumference of the star, where they are generally of a 
very dark tint. As in the Rhapontic, the yellow lines 
run from the centre to the circumference ; but this di¬ 
rection is ordinarily masked by the interposed radial 
systems and the flexuosity of the lines. 
Chinese Rhubarb .—A transverse section shows light 
yellow rays proceeding from the centre to the circum¬ 
ference, and describing very flexuous lines. These lines 
appear often to anastomose, and form in the apparent 
anastomosis a sort of irregular star, the exterior side of 
Fig. 2. Chinese Rhubarb : transverse section, natural size. 
which is furnished with a greater number of rays than 
the interior. This disposition is seen principally in the 
cambium, and arises from the multiplication of the rays 
■of the ligneous layer, which may be easily seen by means 
of a magnifying glass. As in the Russian rhubarb, the 
intervals between the rays are sometimes occupied by 
stars ; but these are less numerous, less distinct, smaller 
and without the brown or blackish circle that character¬ 
izes the others. 
If these three descriptions be compared, it will be seen 
that the French indigenous or false rhubarb is distin¬ 
guished from the exotic or true by— 
(1) . The rectilinear disposition of its rays, which go 
from the centre to the circumference. 
(2) . The presence, upon its circumference, of a brown 
zone, relatively large and especially very distinct. 
(3) . The absence of the radiated systems (stars), so 
numerous in the Russian rhubarb, less frequent, but al¬ 
ways easy to recognize in the Chinese. 
In order to render these descriptions more easily com¬ 
prehended, two engravings are given, one representing a 
transverse section of the French indigenous rhubarb, 
the other a transverse section of the Chinese. As the 
aspect of the latter varies with every root, and every 
piece of a root, it is only possible to represent its general 
appearance. On the contrary, the structure of the indi¬ 
genous rhubarb varies so little that it is only necessary 
to examine one section, bearing in mind that the brown 
zone will be complete or not according as the specimen 
is an entire one, or only a portion of a root, or that it has 
been little or much cleansed. 
LIQUOR FERRI DIALYSATI. 
BY PROFESSOR G. DRAGENDORFF, 
(Dorpat, Russia.) 
I prepare the above in the following manner, which 
mainly is only a modification of the method of Gros- 
singer:—By mixing 300 c. c. liquor ferri sesquichloridi 
of sp. gr. of 1*37, and 100 c. c. of caustic ammonia, sp. 
gr. 0 - 92, a mixture is produced, which after standing 
one or two hours, becomes perfectly clear and dark 
brown. It contains ammonic chloride and ferric hydrate 
dissolved in ferric chloride. From this mixture, sub¬ 
jected to dialysis, ferric chloride and ammonic chloride 
pass into the outer liquid, leaving upon the dialyser a 
brown solution of the colloidal ferric oxide. The latter 
is perfectly tasteless, and, as was shown by Graham, 
capable of being produced perfectly free from ferric 
chloride. (For 30*3 eq. of ferric oxide=Fe 2 0 3 (Fe=28), 
he had 1 eq. FICl. Annal. d. Ch. and Ph., voi. 121, p. 1.) 
This solution is used successfully under the above 
name, and it only devolves upon us to bring it to a definite 
volume, to render at least an approximate determination 
of a dose possible for the physician. This is the main 
difficulty in the way of preparing this substance. 
The solutions of the colloidal ferric oxide possess, as 
has already been mentioned by Grossinger, immense 
powers of attraction for water. In the dialysing drum, 
as I used to employ it, made of parchment paper, I 
always observed, even if the level of the liquid within 
the dialyser was half an inch higher than that of the 
external water, not only a strong outward current into 
the water, but also the reverse from the water into the 
dialyser. In other words, the contents of the dialyser 
possessed a great tendency toward dilution from absorbed 
water. I hardly succeeded in obtaining solutions of 
ferric oxide containing over 4 - 5 per cent. Fe 2 0 3 +3H0, 
some containing only 1*5 per cent. I was forced, there¬ 
fore, to abandon the previously used dialysing drum, 
and to place the iron solution into a pig’s bladder, washed 
with dilute potash lye and then with distilled water. 
The bladder is filled through a funnel and then tied 
tightly as possible, so as to be almost completely filled 
by the solution. The better this is done the less water 
will enter the bladder during diffusion, and the more 
concentrated the liquor will remain. In this manner I 
succeeded in producing a preparation containing 7 per 
cent, of the ferric trihydrate. The great tendency of 
the contents of the dialyser to absorb water may be seen 
by firmly tying the opening of the bladder around a 
glass tube four or five feet high. In this the liquid will 
rise several feet above the level of the dialyser. The 
bladder containing the iron solution is suspended in a 
cylindrical glass vessel, with its upper portion about an 
inch below the level of the water, the quantity of which 
in the outer vessel should be at least four or five times 
