Novemter 23,1872.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
407 
with litmus paper. If it shows an acid reaction, more 
'carbonate of baryta must be added until the reaction is 
neutral. When a sufficient quantity of carbonate of 
bartya has been added, filter and evaporate to 4 fluid 
ounces. It is not necessary to proceed to crystallization, 
.as the salt is very soluble, and therefore difficult to crys¬ 
tallize in small quantities, and a solution of it is really 
what is wanted after all. 
Bromide of Quinia. —To make this salt, dissolve 1 oz. 
of medicinal sulphate of quinia in 32 fluid ounces of 
boiling water, and add solution of bromide of barium 
until a precipitate ceases to be produced. (A little less 
than 5 fluid drachms of the solution of bromide of barium 
made by the formula given above, will be about the pro¬ 
per quantity.) .Filter a small quantity of the solution, 
acidulate it slightly with nitric acid, and test for baryta 
with a few drops of diluted sulphuric acid. If a whitish 
turbidity is produced, it is an indication that too much 
bromide of barium has been added, and enough sulphate 
of quinia must be added to entirely decompose it. If, on 
.the other hand, the presence of baryta in the solution was 
not indicated, slightly acidulate another portion of the 
filtrate with nitric acid, and add a drop or two of solu¬ 
tion of bromide of barium. If this produces a whitish 
turbidity, it shows that there has not been enough bro¬ 
mide of barium added, and more must be very carefully 
.added, until the sulphate of quinia is all or nearly all 
decomposed. It is better, of course, to have a little un¬ 
decomposed sulphate of quinia in the solution than any 
bromide of barium. 
When the precipitation of sulphate of baryta is com¬ 
pleted, filter the solution, while still warm, into a capsule, 
and evaporate at a gentle temperature, until crystalliza- 
iion begins to set in. Then remove from the fire 
and set aside to crystallize. The bromide of quinia 
will be found to be aggregated in globular clusters ^ of 
brilliant silky needles, and the singularly beautiful 
appearance of the crystallization is alone almost ample 
compensation to any one for the little trouble he may 
go to in making it. 
Drain the crystals well, remove them from the cap¬ 
sule, and place between sheets of bibulous paper and 
set aside to dry. The crystals are soluble in about 40 
parts of cold water, and appear to be anhydrous. At 
least I have had a small quantity exposed to the air 
.for a couple of weeks, and they do not show the 
slightest appearance of efflorescence. I have not made 
accurate weighings, and cannot speak positively. 
Bromides of Morphia and Strychnia. —These salts may 
be prepared after the same method as bromide of quinia, 
with slight modifications, which will readily suggest them- 
.eelves. They both crystallize well, aqd are quite as 
soluble as the corresponding sulphates. 
Bromide of Calcium. —The process of Mr. James R. Mer- 
cein, in the March number of the Journal,* * is probably as 
good a one as could be devised. The majority of apothe¬ 
caries, however, will find the following to be a more 
-xeady and convenient way of making it:— 
Dissolve 4 oz. of bromide of ammonium in a pint of 
water. Put in a flask and bring to the boiling-point. 
.Keep boiling, and add milk of limef (made from pure 
calcined lime), in small quantities, until ammoniacal 
vapours cease to be evolved. The operator can easily 
* Phaem. Jouen. [3] vol. ii. p. 878. 
■f- In a note appended to this article, the Editor of the 
Amer. Journ. Pharm. points out that in decomposing bromide 
■of ammonium by caustic lime, care must be taken to avoid an 
excess of the latter, since a basic bromide (oxybromide) of 
calcium is very readily formed, having a strong alkaline reac¬ 
tion. The term bromide of quinia has of late been frequently 
used in medical journals, but is incorrect. The salt being 
.a combination of hydrobromic acid, with the alkaloid quinia, 
.should be called hydrobromate of quinia. Its composition 
is analogous to that of hydrochlorate (muriate) of morphia, 
and its proper name is formed correctly only in perfect 
unalogy with that of the latter. 
tell when this point has been reached, by the sense of 
smell. Filter the solution, evaporate to a syrupy con¬ 
sistency, remove from the fire and stir until cold. This 
salt is quite deliquescent, and requires to be kept in 
well-stoppered bottles. In preparing this salt, care 
must be taken as to the quality of lime used, as some 
limestones contain a large percentage of carbonate of 
magnesia, and the salt obtained by using a lime burnt 
from limestone of that quality, would necessarily contain 
a correspondingly large percentage of bromide of 
magnesium. 
VANILLIC ACID.* 
EY M. r. CARLES. 
After being preserved for a certain time vanilla 
generally becomes covered with crystalline needles. 
As this crystallization is considered to be a mark, of 
good quality, sometimes it is sought to impart it to in¬ 
ferior vanilla, and this is done by simply putting some of 
the crystals already formed into the case containing it. 
The chemical composition of this efflorescence does not, 
however, appear to be perfectly understood. 
Formerly, and the error has been repeated in recent 
works, Vogel asserted that it consisted of benzoic or 
cinnamic acid; Wittstein thought it to be coumarine. 
M. Vee,f comparing the melting-points of these various 
substances, detected the error and showed that it wasa 
peculiar acid. About the same time, M. Gobley % investi¬ 
gated the chemical characters of these crystals, compared 
them with coumarine, and proposed for them the name 
vanilline, or aromatic principle of vanilla. Later, in 
Germany, Stokkebye§ took up the subject. He fixed the 
melting-point at 82° C., instead of 76° C. (Gobley), or 
78° C. (Vee), and in virtue of its acid properties called 
it vanillic acid. Finally, while Gobley had attributed 
to it the formula C 20 H G O 4 , Stokkebye represented it by 
C 34 H 30 O 20 .il These differences in the formulae and melting- 
points 1 attributed to it seemed to show that even if their 
authors examined the same crystals, they were at least 
not of equal purity. M. Carles was therefore induced 
to undertake the present investigation. 
Instead of extracting the vanillic acid directly from 
the vanilla, M. Carles preferred to purify the deposit 
found at. the bottom of the cases in which vanilla had 
been kept. From a mixture of specimens from various 
sources he made a concentrated aqueous solution by 
boiling, and after the addition of animal charcoal, passed 
it through a moistened filter. Upon cooling, the acid 
was deposited, and it was submitted to two or three 
successive crystallizations. If cooled slowly the crystals 
appeared as colourless transparent prisms, sometimes 
more than two centimetres long. When fresh and very 
pure their odour was very feeble, but was increased by 
heat, and their taste was piquant. Vanillic acid, so ob¬ 
tained, melts at between 80 3 C. and 81 C. Heated on 
platinum foil it volatilizes without decomposition, but it 
distils with difficulty in a retort at about 280° C. It is 
very soluble in cold alcohol, ether, chloroform, sulphide 
of carbon and the fixed and volatile oils. Water at 
15° C. dissolves 1-2 per cent., but in boiling water it 
is very soluble. It decomposes the bicarbonates w ith 
effervescence ; and saturates perfectly the alkaline bases 
in the cold, and the earth bases with heat. Pure con¬ 
centrated sulphuric acid turns it yellow in the cold, but 
if the acid contain traces of nitric acid a scarlet colour 
is produced, and the same result follows with, pure sul¬ 
phuric acid and resinous crystals. Dilute nitric acid 
attacks it feebly, but concentrated quickly, converts it 
into oxalic acid. Chlorine, bromine, and iodine yield 
products of substitution. It is precipitated by acids 
from concentrated aqueous or alcoholic alkaline solutions 
* Abstract of paper in ‘ L’ Union Pharmaceutique, xiii. 294. 
+ Journ. do Pharm. et deChimie, [3] xxxiv. 412. + Ibid. 404. 
§ Zeitschrift fiir Chemie, 1865, p. 467. 
I |[ These formulce are according to the old notation. 
