974 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[June 7, 1873, 
tions between the bases of the gum and the organic matter 
are constant, and are not dependent upon circumstances 
by which the quantity of lime might be augmented or 
decreased. 
Preparation and Properties of Metagummic Acid .—One 
principal reason why metagummic acid so long remained 
unknown was, that it is not produced except under special 
circumstances. Gffiis had, it is true, shown that gum 
became insohible in water after exposure during several 
hours to a temperature of 125° C., and that it again 
became soluble if it were boiled in water a sufficiently 
long time. It was also known that in heating a concen¬ 
trated solution of gum with strong sulphuric acid, besides 
sulphate of lime, an insoluble viscous body was precipitated. 
But the examination of the bodies so obtained could not 
be carried further, since through the quantity of lime 
present in the first it became too soluble when experi¬ 
mented on, and the second could not be freed from the 
sulphate of lime and the sulphuric acid. The plan adopted 
by the author is to pour a cooled mixture of 50 c. c. of 92° 
alcohol, 10 c. c. of water, and 5 c. c. of strong sulphuric 
acid, upon 25 grams of perfectly pure gum, and allow them 
to remain together for twenty-four hours, stirring fre¬ 
quently. The whole is then thrown upon a filter in con¬ 
nection with an air-pump, and the undissolved portion is 
washed several times with alcohol. It is then placed in a 
vessel nearly full of distilled water, shaken and washed by 
decantation until it gives no reaction either of lime or of 
sulphuric acid. The metagummic acid has then the ap¬ 
pearance of a slightly opaline, colourless, translucent jelly, 
of which the volume is ten or twelve times that of the 
gum employed to produce it. In order to dry it, it is 
shaken in a linen bag to remove moisture ; then placed in 
a vessel and alcohol poured upon it. This causes it to 
contract a little ; the supernatant liquor is removed, and 
fresh alcohol poured on. It becomes pulverulent, is thrown 
on a filter, and, when drained, the powder is pressed be¬ 
tween linen and left to dry in the air, which it does in a 
few minutes. 
Metagummic acid so dried resembles exactly white 
gum arabic, with a slight yellow tint; reduced to a fine 
powder it is perfectly white. It has neither odour nor 
taste, but it exercises a decided acid reaction upon blue 
litmus paper. It will absorb 15 per cent, of water from 
the air, but without becoming humid. It is not soluble in 
cold water,—which causes it to swell into a voluminous 
gelatine,—or in boiling water. It dissolves, however, in 
dilute alkaline solutions, when the alkali does not exceed 
the quantity necessary to dissolve it. When there is excess 
of alkali the solution acquires a colour varying from yellow 
to dark brown, in consequence of the decomposition that 
takes place ; metagummic acid is thereby changed into 
gummic acid, and in this manner salts of potash, soda, 
magnesia, baryta, etc., may be obtained, which all form 
colourless and mucilaginous solutions like gum. Acids do 
not precipitate metagummic acid from these solutions, but 
if they are evaporated to dryness and treated as before 
with alcohol and sulphuric acid, metagummic acid is re¬ 
produced. 
The author also obtained the metagummic salts of 
copper and of zinc : the first is insoluble and forms a pale 
blue precipitate ; the zinc salt is slightly soluble. 
Fremy found the elementary composition of meta¬ 
gummic acid to be— 
I. II. III. 
Carbon . 41T0 40*82 40*96 
Hydrogen . 5*93 6T6 6*01 
Oxygen . 52*97 53*08 53*03 
According to this its formula would be C 7 H 6 0 7 , ap¬ 
proaching the formula of metapectic acid, C 8 H 5 0 7 . Hence 
it would appear to resemble the pectic or gelatinous bodies, 
rendering the hypothesis probable that gum is due to phe¬ 
nomena analogous to those which give rise to the pectic 
bodies. The resemblance would be still more complete if 
future research should discover in plants a substance 
analogous to the pectones, of which gum would be a pro¬ 
duct of transformation. 
It will be seen from the foregoing that gum arabic 
cannot be considered an immediate vegetable principle, 
but rather a mixture of the metagummates of potash, 
lime, and magnesia.’ Experiment has not yet shown 
whether the proportions of these salts in gums are always 
the same; but it is probable that they are very variable, 
for there is no reason why these several bases should not 
substitute one another, according to the nature of the. 
soil. The substitution would have no effect upon the 
appearance of the gum or its properties; the various 
metagummates all forming colourless solutions of the 
same consistence, except the ammoniacal salt, its solution 
being more liquid than the others. All these bases are 
chemically combined with the gummic acid. 
Preparation of Gummic Acid .—For this purpose pure 
metagummic acid was dissolved in an exactly-measured 
quantity of lime or baryta water. A sufficient quantity 
of oxalic or sulphuric acid—according as lime or baryta 
was used—was added to neutralize the alkali. As the 
milky liquid so produced could not be cleared by filtration, 
it was allowed to stand some time. In this manner a 
solution of gummic acid was obtained, still a little opaline, 
but perfectly colourless. Evaporated to dryness it yielded 
a transparent, hard, brittle substance, an aqueous solution 
of which was strongly acid, and less viscous than a solu¬ 
tion of an equal quantity of ordinary gum. Its reactions 
with alkalies and their salts were the same as those of 
metagummic acid. 
NOTE ON ACONITE ROOT.* 
BY EDWAKD R. SQUIBB, M.D, 
There is good reason to believe that the appreciation of 
the value of preparations of aconite root in therapeutics, 
and the increasing use of these medicines, are hindered 
by the want of uniformity in quality of the root as. met 
with in the markets, and the custom of pharmacists gene¬ 
rally of buying by appearance, or what is still worse, 
buying in powder. The writer has been for some years 
past almost constantly in search of this drug of proper 
quality for medicinal use, and has been frequently out of 
it and its preparations through inability to find it in the 
markets of the seaport cities of this country, and has even 
failed tc get it in London. Yet if quality be not con¬ 
sidered or not tested, there are few drugs more easily or 
more cheaply attainable at all times. From the large 
brown root, which rarely is, though often is called, 
“English,” to the small black root commonly known as 
“ German,” the markets are always abundantly supplied 
with root of various sizes and shades of colour. The 
general appearance is almost always good, and the root 
clean and sound, and even on fracture, the substance of 
the root appears to be of fair quality. Upon testing, 
however, it will often be found that not more than four 
or five roots in ten have any medicinal activity, and these 
only in feeble degree. Occasionally parcels will be met 
with in which every root possesses the desired activity, at 
least in some notable degree. Thus it becomes necessary 
to decide upon some arbitrary standard of strength to 
govern the selection, and in the present state of the 
markets this must not be set too high, if anything like a 
uniform supply of fresh preparations is to be kept up. 
The arbitrary rule adopted by the writer many years ago 
was not to buy any parcel from which six roots out of ten 
did not yield a fair degree of medicinal activity, and to 
get as much above this as possible. Within the past two 
years the quality in the United States market has im¬ 
proved, and now the arbitrary rule has been changed, and 
eight roots out of ten from an ordinary handful sample is the 
# From the ‘Proceedings of the American Pharmaceu¬ 
tical Association,’ 1872. 
