Monthly retrospect of the medical sciences : January to December 1849 / edited by George E. Day, Alexander Fleming, W.T. Gairdner.

Date:
MDCCCXLIX [1849]
Catalogue details

Licence: Public Domain Mark

Credit: Monthly retrospect of the medical sciences : January to December 1849 / edited by George E. Day, Alexander Fleming, W.T. Gairdner. Source: Wellcome Collection.

    218/262 page 216
    aided with a little heat; it is insoluble in spirit. The spurious valerianate of quina is soluble in about thirty parts of boiling water, and, as the solution cools, it is deposited in acicular crys¬ tals, which have the bitter taste and other characters of disulphate of quina. 3. The true valerianates, when mixed with a little diluted hydrochloric acid, are decomposed, and the valerianic acid being set free, rises like oil to the surface of the liquid. To get this character, it is neces¬ sary to operate upon from five to ten grains of the specimen, and to avoid the use of too much of the diluted acid, as valerianic acid is soluble in about thirty parts of water. The liberated valerianic acid has the sour, disagreeable, and very persistent smell, which, to a slight extent, is perceived in its salts, but it is readily distinguished from that of oil of valerian. 3. The spurious valerianates, when add¬ ed to water, will generally yield a thin film of oil, which floats on the surface, and is easily detected as oil of valerian. On heating the liquid this oil is driven off, without other¬ wise decomposing the salt, and no further indication of valerian will af¬ terwards be obtained. On treating them with diluted hydrochloric acid, there is no valerianic acid set free. 4. The true valerianates, when mixed with a little proof spirit, and one-fourth the volume of oil of vitriol is then care¬ fully added, will yield valerianic ether, which is recognised by its agreeable fruity smell, somewhat resembling that of the pine- apple. This ether can hardly be dis¬ tinguished in smell from butyric ether. 4. The spurious valerianates yield no valerianic ether; but the spurious valerianate of zinc, when treated as above, yields acetic ether, which is easily detected. The foregoing tests are sufficient to distinguish the true valerianates from the spurious substitutes above-mentioned, but there is reason to believe that other sub¬ stitutions have been practised, although not so extensively. We have met with a specimen of so-called valerianate of iron, which is evidently not what its name indi¬ cates, and yet it contains neither citrate, tartrate, nor acetate. It is in the form of a brown powder, insoluble in water and in spirit. It smells of valerianic acid, but on being decomposed with hydro¬ chloric or sulphuric acid, yields no appre¬ ciable quantity of the oily product. We have not had time to submit this specimen to a careful examination, but it is easily distinguished from the true valerianate of iron by its being insoluble in spirit, while the latter dissolves freely in this men- strumum, even without the application of heat. This suspected specimen is also distinguished from the genuine by its- behaviour when heated in a platinum crucible. The true valerianate, if carefully heated, fuses, gives off valerianic acid undecom¬ posed, then as the heat is increased, burns with a luminous flame, and emits a very offensive odour. The suspected specimen does not fuse or give off any appreciable quantity of valerianic acid. The vapour does not readily inflame, and the odour emitted is not offensive. The residue of oxide of iron is the same in both specimens, namely, twenty- five per cent., and the acid originally pre¬ sent is organic. Where mere adulteration is practised, the detection of the fraud is much more difficult than it is in the cases to which we have hitherto alluded, the cupidity of the manufacturer having fortunately, in these cases, blinded his discretion, so that a speedy exposure of the practice was in¬ evitable. About three years ago, as we find from the “ Journal de Pharmacie,” much of the valerianate of zinc met with in Paris was found to have been made with butyric acid, instead of valerianic acid. The buty¬ rate thus substituted was of a more beauti¬ ful and crystalline appearance than the true valerianate, but it did not essentially differ in character, and the detection of the fraud, by satisfactory tests, was not easily accomplished. A paper was published on the subject by Mes.srs Laroqire and Hur- aut, in which they recommend the use of a concentrated solution of acetate of cop¬ per for distinguishing valerianic from buty¬ ric acid. In the use of this test, however, it is necessary, in the first place,- to elimi¬ nate the acid by adding sulphuric acid to the salt and separating the volatile acid by distillation. When butyric acid is added to the concentrated solution of acetate of copper, a bluish white precipitate is imme¬ diately formed ; hut on adding valerianic acid in like manner, there is no immedi¬ ate appearance of precipitation or turbi¬ dity of the liquid, but on shaking it, oily drops, of a greenish colour, separate, partly rising to the surface and adhering to the sides of the vessel, and partly falling to the bottom. These oily globules consist of anhydrous valerianate of copper, which retains this condition sometimes twenty minutes or more, but it ultimately becomes hydrated, and then forms a bluish green crystalline powder_Ph. J,, June 1849.
    digitised image 1
    digitised image 2
    digitised image 3