Analytical reagents : standards and tests / compiled by Edmund White.

Date:
1911
Catalogue details

Licence: In copyright

Credit: Analytical reagents : standards and tests / compiled by Edmund White. Source: Wellcome Collection.

    12/194 (page 6)
    fixed upon an arbitrary basis of percentage, but some fraction of the molecular weight of the substance in question is contained in a litre of the solution, that is, the solutions are approximately normal solutions. For qualitative reactions it is sufficient to weigh carefully the indicated quantity of substance, and dissolve it in the solvent to the required volume. Equal volume of the various solutions will thus be equivalent or will bear some simple relationship to each other. The advantage of this system is particularly obvious in the case of acid and alkaline solutions which may be used alternately to render a liquid acid or alkaline, since the volume of an acid solution added as a reagent may be afterwards neutralised with certainty by the addition of an equal volume of the alkaline solution and vice versa. The brief notes under “Trade Varieties” are intended to indicate the nature and composition of chemicals met with in trade, and will be amplified in subsequent issues if the information proves acceptable to readers. The Reagents complying with the tests described may be obtained from Messrs. Hopkin & Williams, Ltd., by adding the word “ Reagent ” to the name of the chemical, or more briefly the capital letter “R.”: thus Sodium Carbonate R. If ordered through a dealer the letters in brackets (H. & W.) should be added. All the substances so described are prepared and purified by Messrs. Hopkin & Williams, Ltd., and are issued with the label, of which a facsimile is appended.