THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[January 27,1872. 
GU 
CHEMICAL SOCIETY. 
Thursday, January 18th ; Dr. Fiiankland, F.R.S., 
President, in the chair. At this meeting Dr. Odling 
exhibited some very fine specimens of rare metals and 
their compounds which |had been lent to him by Dr. 
Richter and Dr. Schuchardt. Amongst these was a bar, 
weighing about seven ounces, of metallic indium, an 
element discovered a few years ago by Dr. Richter in 
conjunction with Reich; also some metallic rubidium. 
Mr. David Howard then read an interesting paper on 
“Quinicine and Cinchonine and their Salts.” These 
■alkaloids are prepared artificially from quinine and cin¬ 
chonine respectively, by the action of heat on their salts, 
and are isomeric with them. Quinicine occurs along 
with the two last-mentioned alkaloids in cinchona bark 
(Peruvian bark), being apparently the one which is 
first formed during the growth of the cinchona plant. 
SOCIETY OF ARTS. 
Dyes and Dye-Stufes other than Aniline.* 
BY DR. CRACE-CALVERT, F.R.S. 
Lecture IV. 
Quercitron , Fustic , Persian Berries , Weld , Aloes , Turmeric , 
Annatto , Ilixanthine , Lakao , Tannin matters , Gall-nuts , 
Sumach , JJivi-divi, Myrobalans , Catechu. 
[Concluded from page 575.) 
Gallic acid presents itself under the form of fine, w r hite, 
silky needles, and is soluble in water, alcohol and ether. 
Under the influence of a temperature of 410° F., it un¬ 
folds itself into carbonic acid and a beautiful white crys¬ 
talline compound, called pyrogallic acid, which has of late 
years been extensively employed in photography. If 
the temperature be raised to a higher point than the one 
above mentioned, gallic acid is decomposed into carbonic 
acid, water and gallhumic acid. The first decomposition 
may be represented by the formula?— 
C 7 H # 0 5 = C0 2 + C fi H f[ 0 3 ; 
Gallic Carbonic Pyrogallic 
acid. acid. 'acid, 
the second as— 
C,H ? O s = C0 2 + H 2 0 + C fi H 4 0 2 . 
Gallic Carbonic Water. Gallhumic 
acid. acid. acid. 
Gallic acid has been produced artificially by the action 
of potash on a di-iodosalycilic acid. When sulphuric 
acid is made to act on gallic acid, it transforms it into 
a red acid called rufigallic, which has the formula 
€ 7 H 4 0 4 . When in contact with alkalies, or in pre¬ 
sence ot air, gallic acid, like pyrogallic and tannic acids 
and various other organic substances, rapidly absorbs 
oxygen, as was shown by M. Chevreul in 1820. On 
this fact, Liebig, in 1838, founded an elegant method of 
determining the amount of oxygen in a mixture of gases. 
The process is, however, only approximately correct, as 
I proved m 18C3 that under these circumstances oxide 
of carbon was liberated. 
Gallic acid gives a purple-black precipitate with per- 
salts of iron, but none with the proto-salts. It gives no 
precipitate with gelatine, which is a most important fact, 
ns I shall now proceed to show. 
Tannin matters, such as oak-bark, are employed for 
fanning leather, and the conversion of a hide into'leather 
depends on the gradual transformation of the animal 
matter which it contains into gelatine. This combines 
•with the tannic acid, producing an insoluble compound 
which fills the pores of the animal tissue, and thus con¬ 
tributes, not only to prevent its putrefaction, but to 
render it impermeable to water. The value, therefore, 
of a tannin matter depends on the amount of tannic acid 
* Cantor Lecture, delivered Tuesday, Feb. 28. Reprinted 
from the Journal of the Society of Arts. 
it contains, the gallic acid taking no part in the tanning 
of the hide. 
Tannin substances, such as gall-nuts, sumach, or bark, 
contain a ferment, which is susceptible of unfolding the 
glucoside tannic acid into sugar and gallic acid. It is 
necessary, therefore, that the tanner take great care in 
the management of the vats, to prevent any fermenta¬ 
tion, especially the one called ropiness, for in suck a case 
the vat would become useless. As it is a difficult matter 
often in summer to prevent this state of things. I may 
state that I have found that the addition of a few thou¬ 
sandths of carbolic acid is sufficient to prevent these che¬ 
mical changes, without interfering with those which 
must take place in the hide. 
Tannin matters, as you are aware, are much employed 
for producing blacks on fabrics, mordanted with per¬ 
oxide of iron. I asked myself some years since, whether 
it was the tannic or the gallic acid which produced the 
black, or if both participated in its production ; and the 
results of my experiments clearly proved that tannic acid 
alone took part in its formation. This may be seen if 
two pieces of calico mordanted -with iron are dipped, the 
one in a solution of tannic acid, and the other in a solu¬ 
tion of gallic acid. Both pieces at first become dyed, but 
after a few days, the one dipped in tannic acid remains 
black, w T hile in the one dyed with gallic acid the colour 
has disappeared, the gallic acid having reduced the per¬ 
oxide of iron to the state of protoxide, which, as I have 
already remarked, does not produce a black with these 
acids. 
As gallic acid is of no value to the dyer as a colour- 
giving principle, he must take care that his tannin mat¬ 
ters, such as sumach, are carefully stored and kept dry, 
so as to avoid any gallic fermentation taking place, 
which would decrease the amount of tannin they contain. 
He should also avoid holding a large stock, as the fer¬ 
mentation above mentioned slowly proceeds in the tannin 
matters, as is proved by the fact of sumach, for example, 
decreasing considerably in value after it has been some 
time prepared. 
I shall now proceed to give you a brief outline of the 
characteristic differences of the several tannin matters. 
Gall-nuts are the most valuable and important of all 
tannin matters. They are produced by the female of an 
insect called Cynips , which pierces the buds on the young 
branches of the Quercus infect or ia, a tree growing espe¬ 
cially in the East. There she soon deposits her eggs, 
and the bud loses its natural growth, and swells out to 
the size of a hazel-nut, having a green, red, or pink 
colour. The eggs thus enclosed soon hatch, and the in¬ 
sect undergoes all its metamorphoses until it attains the 
perfect state, when, if allowed (which is not to the in¬ 
terest of either the gatherer or consumer), it makes a 
hole and escapes. Good gall-nuts should not be so 
pierced, and they should be heavy, and of a fresh green 
colour. If the insect has escaped they are yellow, and 
are not of nearly so good quality. 
In the market, they generally bear the name of the 
port from which they were shipped. Thus, there are 
Aleppo gall-nuts, which are considered the best in the 
market, then the Morea, Smyrna, etc. 
The following may be considered as the composition 
of an average sample of gall-nuts:— 
Tannic acid. 
. . 65-0 
Gallic acid. 
. . 2-0 
Ellagic acid ) 
Luteo-gallic acid J * * * * 
. . 2-0 
Chlorophyll and volatile oil . 
. . *7 
Brown extractive matter . . 
. . 2 - 5 
Gum. 
Starch. 
Lignine. 
Sugar, albumen, etc., and ash 
. . 1-3 
Water. 
. . 11-5 
100-0 
