202 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. [September 14, 1872. 
first formed have been drained in a funnel, they may 
be obtained nearly pure simply by washing them 
with gasoline, and require then one crystallization 
from alcohol or petroleum benzine to be entirety 
pure and unaltered hi the light. The monobromated 
camphor dissolved by the gasoline may be recovered 
by evaporating most of the solvent spontaneously, 
washing the crystals with a little gasoline and re¬ 
crystallizing. The remaining mother-liquors, if not 
uspd as solvents in subsequent operations, may be j 
worked up with the oil left by the first crystallization. 
While experimenting with bromide of camphor, 
W. H. Perkin,* in 1805, obtained monobromated 
camphor by treating the oity matter obtained from 
the action of bromine and camphor with hot solution 
of potassa, and subsequently heating the product in 
a retort, collecting that portion of the distillate sepa¬ 
rately which comes over above 36-4° C. (508° F.). 
T. Swarts,f however, prefers the process suggested 
by him to that of Perkin, regarding the former as 
more satisfactory; he also states that when moist 
monobromated camphor is distilled, or it is left in 
contact with hot water, bromine and hydrobromic 
acid are evolved, and camphor free from bromine is 
separated. The regeneration of camphor under these 
circumstances has never been observed by me: on 
the contrary, when the monobromated compound is 
boiled in a retort of water, a white crystalline subli¬ 
mate resembling snow-flakes is slowly formed in the 
neck of the retort, and these crystals contain bro¬ 
mine, and have all the behaviour of monobromated 
camphor. 
Perkin observed that monobromated camphor, 
treated with alcoholic ammonia in a sealed tube, at 
180° C. (356° F.), undergoes a slight decomposition, 
with the formation of an organic base and of ammo¬ 
nium bromide. Fearing that the prolonged action 
of hot potassa solution upon the oil which already 
contains monobromated camphor might induce its 
decomposition, and my time not permitting to inves¬ 
tigate it, I had resort to carbonate of lime (white 
marble), which, as previously observed, was found 
to answer the purpose well, as far as the removal of 
hydrobromic acid was concerned. On heating the 
remaining oity matter gradually, it was found to 
turn blacldsh when nearing 150° C. (300° F.), the 
colour became darker as the temperature rose, and 
a little oil distilled over, which solidified after a 
while and turned red from the liberation of some 
bromine. Meanwhile, the flake-like sublimate in 
the neck of the retort increased considerably, and the 
hot liquid boiled actively between 260° and 201 y C. 
(500° and 502° F.), disengaging considerable quanti¬ 
ties of hydrobromic acid, and separating also so much 
charcoal that the retort cracked. Eight ounces of 
bromine had been used in this experiment, the black 
residue of which, when dissolved in alcohol and 
filtered, yielded white crystals, requiring to be re- 
crystallized once, while the mother-liquor had a 
strong acid reaction, due to free hydrobromic acid. 
Although this experiment was not very favourable 
for Perkin’s process, in its application to the prepa- 
tion of this compound on a large scale, it suggested a 
method of utilizing the oily residue which had accu- 
* ‘ Journal of tlie Chemical Society,’ new series, iii. 92 ; 
Annalen d. Chem. u. Pharm. Suppl. iv. 124 ; and Will’s 
Jakresberickt, 1865, 570. 
f ‘ L’lnstitut,’ 1866, 287. Will’s ‘ Jahresbericht,’ 1866, 
622. 
initiated from the mother-liquors of the first crystal¬ 
lization of monobromated camphor prepared at a 
lower temperature. The grey granular mass, left 
by expressing a portion of the solidified oil, as stated 
above, was slowly heated to 200° C. (500° F.), and 
after the disengagement of most of the hydrobromic 
acid, was dissolved in petroleum benzine, treated 
with marble and filtered, when monobromated cam¬ 
phor crystallized. The oity residue, containing some 
of the granular compound, was next treated in the 
same way, with a similar result. In both cases 
some of the oity mass was left in the mother-liquor, 
which may undoubtedly be utilized in a subsequent 
operation. 
(To be continued.) 
LABORATORY NOTES.* 
BY EDWARD SMITH, F.C.S. 
Bromide of Potassium .—This salt is generally found 
in commerce of a high degree of purity. This is not, 
however, always the case, a sample sent to me proved 
to be contaminated with chloride of potassium. The 
amount of chloride was estimated as follows, iodides, 
iodates, and carbonates having been previously ascer¬ 
tained to be absent:— 
•0640 grains of the dry salt were titrated with 
solution of silver nitrate, potassium chromate as indi¬ 
cator, 55*5 c. c. of ^silver were required to complete the 
reaction, and 
55-5 x -00119=;-0660 ; the volume of silver solution used 
is therefore in excess of that required for pure potassium 
bromide, for -0640 (amount taken) should require 
53’78 c. c., since •0640-r-‘OOllk—53'78 and 
51*0 c. c. silverX , 00119zz , 06069 KBr. 
4’5 c. c. cty silverx *000745~ , 00335 K Cl. 
55’5 c. c. zz *06404 K Br-f-K Cl. 
and -00335^-0640xlOOzr 5.20 
•06069 -t- ‘0640 X 100-94-80 
The sample, therefore, contained 5*2 per cent, of chloride 
and 94-8 per cent, of bromide of potassium. 
Acetic Acid .—Iron is not usually mentioned in the 
text-books as an impurity in this acid. A small amount 
of iron proves very tiresome, since, if the acid be used for 
preparing mindererus, the iron is constantly and gradually 
depositing. On examining some acid which hadbeen partly 
used in making mindererus, I found it to contain iron 
and manganese, the proportion of the former metal was 
2-67 grains to an imperial pint. The manganese was 
not estimated, but'was very readily detected in the iron 
sulphide (thrown down by ammonia sulphide from the 
neutralized acid) before the blow-pipe. In every other 
respect the acid was satisfactory. 
Glycerine .—The high price of English glycerine has 
encouraged the introduction of foreign supplies. English 
glycerine, as a rule, stands the Pharmacopoeia tests of 
gravity, etc., well. Continental samples, although pro¬ 
fessedly pure, and “equal to Price’s,” are not always 
reliable; either the gravity is low, or they are not 
odourless, or perfectly free from metallic impurity. One 
specimen, apparently pure, I found to contain a notable 
amount of some sulphur compound (not determined) 
probably arising from IL.S having been used to free the 
glycerine from metals. It had a sp. gr.~ 1’250, without 
odour, free from metallic impurity, and generally stood 
the usual tests. On warming gently with dilute acid, 
* Read at the Brighton meeting of the British Pharma¬ 
ceutical Conference, August 14, 1872. 
