January 6, 1872.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
513 
M. Falieres next indicates tlie proper method for 
ascertaining the presence of potash, carbonate of 
potash, bromate of potash, sulphate of potash and 
nitrate of soda. 
Upon a small piece of iodine being thrown into 
a solution of bromide of potassium the liquor will 
assume a yellow tinge if the bromide be neutral, but 
it will remain uncoloured if it contain potash or 
carbonate of potash. The latter salt may be de¬ 
tected by means of lime or salts of baryta ; the pre¬ 
cipitate is soluble with effervescence in acids. The 
presence of bromate of potash may be detected by 
heating some of the solution with colourless hydro¬ 
chloric acid. The solution takes a yellow tinge if 
it contains bromate of potash, but remains colourless 
if the bromide be pure. 
M. Falieres states that he has found nitrate of 
soda in many specimens of bromide of potassium of 
English manufacture. This fraud occupied his par¬ 
ticular attention in consequence of the difficulty of 
its detection. As nitrate of silver exercises no action 
upon nitrate of soda, its presence might be unsus¬ 
pected unless it were specially sought for. When a 
mixture of bromide of potassium and nitrate of soda 
is treated with strong sulphuric acid in excess, hydro- 
bromic acid and ruddy vapours of bromine and hypo- 
nitric acid are formed. If the bromide of potassium 
be pure, white vapour of liydrobromic acid is abun¬ 
dantly disengaged, and a small quantity of reddish- 
yellow vapour of bromine. M. Falieres thinks that 
these reactions would be sufficiently distinct; but 
the gentlemen who reported on the memoir to the 
Academy consider that when the quantity of nitrate 
of soda is small, the result would not be clear. They 
recommend that in that case the nitric acid should 
be estimated by one of the known volumetric methods, 
and the bromine by a titrated solution of nitrate of 
silver. 
The second part of the memoir is devoted to dis¬ 
cussion of the best mode of preparing pure bromide 
of potassium. If the ordinary manufacturing pro¬ 
cess of preparing bromine from the mother liquors 
of soda is considered, together with the composition 
of caustic potash, it will be seen how easily the bro¬ 
mide of potassium prepared from them may become 
contaminated by the salts already noticed. M. 
Falieres therefore turned his attention to discovering 
a means of obtaining bromine and potash completely 
pure for the purpose. The elimination of iodine 
from bromide of potassium may be easily accom¬ 
plished by the process of M. Baudrimont, which 
consists in boiling the iodized bromide with an ex¬ 
cess of bromine water, when the iodine that is 
driven off by ebullition is replaced by the bromine. 
The liquor is afterwards evaporated to dryness, to 
drive off excess of bromine. 
The process recommended for the purification of 
bromine is based upon the following reaction. If a 
solution of bromide of potassium be poured into a 
saturated aqueous solution of chloride of bromine, 
the mixture becomes turbid, and pure bromine is 
thrown down ; and if the mixture be heated to drive 
off excess of bromine and of chlorine, the supernatant 
liquor will contain only chloride of potassium, the 
bromine of the chloride of bromine and the alkaline 
bromide being set free and deposited. Consequently, 
if commercial bromine be treated with a slight ex¬ 
cess of bromide of potassium, the bromine will be 
deprived of any chlorine it may contain. Such salts 
as nitrates, bromates, sulphates and chlorides will j 
remain in solution; but any iodine that may be 
present will be precipitated with the bromine ; from 
which it may be easily purified by the process before 
mentioned. 
Potash alcohol being too expensive, and caustic 
potash always containing foreign matters, M. Fa¬ 
lieres proposes to employ purified bicarbonate of 
potash in the preparation of bromide of potassium. 
100 grams of the bicarbonate are dissolved in 
500 grams of distilled water, to which is added 
80 grams of pure bromine. When the disengage¬ 
ment of carbonic acid has ceased, a solution, com¬ 
posed of 90 parts of water and 30 parts of ammonia, 
sp. gr. *875, is poured in. It is then evaporated to 
dryness, and the residue heated until white ammo- 
niacal vapours are no longer given off. The salt is 
then fused, in order to convert the bromate into 
bromide. The product is redissolved in bromine 
water, evaporated and set aside to crystallize. It is 
important to notice that in this process the bromide 
of ammonium reacts upon the undecomposed car¬ 
bonate of potash and converts it into carbonate of 
ammonia, which is volatilized. The bromate so 
obtained does not appear to contain the least trace 
of carbonate. 
M. Castelliaz, who has proposed to replace in 
medical practice the bromide of potassium by that of 
sodium, prepares the latter by an analogous process, 
treating the bromide of ammonium by an equivalent 
quantity of pure soda or carbonate of soda. He ob¬ 
tains the pure bromide of ammonium by letting 
bromine fall drop by drop into ammonia diluted by 
distilled water, and conducting the operation in a 
j Woulfe’s apparatus, in order to avoid loss. The 
evaporation is accomplished in an iron retort, and 
the disengaged vapours collected in a stone-ware 
receiver. The decomposition of the bromide of am¬ 
monium by the carbonate of soda is also carried on 
in an iron retort communicating with two large 
vessels for the condensation of the vapours. 
TRANSFORMATION OF A SOLUTION OF 
CANE-SUGAR INTO GLUCOSE UNDER 
THE INFLUENCE OF LIGHT. 
BY M. E. M. BAOULT. 
The author, in a short note presented to the 
Academie des Sciences, 5 " says that the idea that a 
solution of cane-sugar, kept at the ordinary tempe¬ 
rature, and protected from the action of ferments, 
will preserve indefinitely its flavour and chemical 
properties, is an error. He states that he has often 
observed such a solution, without undergoing the 
least fermentation, to become altered, and at length 
transformed, more or less completely, into glucose; 
and during the present year he has made the follow¬ 
ing experiment, which shows that this change takes 
place under the influence of light:— 
On the 12th of May, 10 grams of white sugar were 
dissolved in 50 grams of pure water. Equal volumes 
of this solution being introduced into two tubes of 
white glass were boiled for some minutes, and the 
tubes closed at a flame before the re-entry of air. 
The tubes so prepared were placed, one in complete 
darkness, the other in a good light; but, at the 
same time, they were kept side by side, that they 
might be subjected to the same variations of tempe- 
* Compteo Rendus, vol. lxxiii. p. 1019. 
