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BEITISH PHARMACEUTICA.L CONFERENCE. 
at once by its solution effervescing with an acid. If tlie valerianate of soda 
is contaminated in this way, the result obtained is unsatisfactory, owing to 
the admixture of hydrated oxide of iron. 
Mr. Hanbury, in writing to me respecting the preparation of the salt, says : 
“We prepare it by decomposing a strong solution of persulphate of iron by 
one of valerianate of soda. Upon mixing the solutions a copious precipitate of 
an extractiform substance of a brick-red colour is formed, with which is mixed 
a considerable quantity of sulphate of soda in small crystals. The precipi¬ 
tate is easily washed by kneading it in distilled water until the latter almost 
ceases to be affected by a solution of baryta. The resulting product requires 
no drying beyond the pouring off, as far as possible, of the water which some¬ 
what gradually exudes from the mass ; it remains in the form of a soft 
extract, which becomes harder after some months. We never attempt to 
dry it.” 
The method I have adopted myself in preparing the specimen now before 
you is, to take any convenient quantity of valerianic acid which is to be ex¬ 
actly saturated with a concentrated solution of carbonate of soda, heating 
the mixture in a water bath so as to dispel all the carbonic acid; the fluid is 
then sufiered to cool and into it is poured, as long as any precipitate is pro¬ 
duced, the liquor ferri persulphas of the British Pharmacopoeia,—about the 
same quantity by measure is required of the iron solution as has been used' 
of valerianic acid; after some little mixing with a glass rod the precipitate 
settles down into a semi-fluid extract, which may be repeatedly waslied with 
distilled water by a sort of kneading process, until the sulphate of soda is 
entirely removed; it is then spread out as thinly as possible upon glass or 
porcelain plates, and suflered to dry either by simple exposure to the air or 
by a gentle heat, then chipped off and preserved in bottles. The salt so ob¬ 
tained is not in the slightest degree deliquescent. 
The best test of its purity is its complete insolubility in water and the ease 
with which it dissolves in spirit of wine. 
Yalerianate of Zinc. 
The question proposed for solution in the list of subjects now under the 
notice of the Conference in connection with this substance is ;—Describe an 
easy method of determining the purity of valerianate of zinc as found in 
commerce ? In answer to this, I wish to say that I have not had time to 
carry out any great number of experiments on the subject, but I find that 
pure valerianate of zinc dissolves readily in a dilute solution of citric or tar¬ 
taric acid, without separation of the valerianic acid, as is the case when sul¬ 
phuric or hydrochloric acid are used. Oxide of zinc is insoluble in dilute 
vegetable acids, so that supposing a sample were tested which had been made 
by rubbing up valerianic acid with oxide of zinc, the specimen would remain 
insoluble. If acetate of zinc had been used as a substitute, this would dis¬ 
solve, but it would also dissolve in water. Therefore, if a specimen is tested 
and found to be insoluble in water but dissolves pretty readily in a cold weak 
solution of citric or tartaric acid, we may infer that the preparation is pure. 
A Member remarked that he had been told by a manufacturer that it was a common 
practice to prepare valerianates of iron or of zinc, and then to add a further portion of 
the oxides of those metals. 
