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.

    107/194
    Iron and Heavy Metals: Dissolve 1 Gm. in 20 mils of water, add 5 drops ammonium sulphide solution ; no darken- ing should occur. Trade Varieties. Under the name of Epsom Salts, this article is very largely used in medicine. The lower grades are commonly sold in sacks, and contain much foreign matter, and hence cannot give bright solutions in water. The purified article required by most pharmacopoeias for use in medicine are fairly clean, and contain only small traces of iron. The purified and recrystallised salt described above is in brighter and largeT crystals than the ordinary Epsom Salts of trade. MANGANESE CHLORIDE. MnCl24H20. Reddish-pink crystals. Hygroscopic. Tests. Solubility: Soluble in about its own weight of water. Sulphates: 1 Gm. dissolved in 20 mils of water with 5 drops hydrochloric acid should give no precipitate on the addition of 1 mil barium chloride solution afte~ standing one hour. Iron: Dissolve 1 Gm. in 50 mils of water, add 5 drops hydrochloric acid and 1 mil chlorine water. Boil, cool and add 2 mils potassium thiocyanate solution : no red colour should be immediately produced. Magnesium and Alkalies: Dissolve 2 Gms. in 50 mils of water, add 3 Gms. of ammonium carbonate dissolved in 50 mils of water, warm the mixture, set aside to cool and then filter. Evaporate the filtrate to dryness and ignite the residue, which should weigh not more than 1 Mgm. Calcium: 1 Gm. dissolved in 50 mils of water with the addition of 2 mils ammonium oxalate solution should give to immediate precipitate. Zinc: 1 Gm. dissolved in 20 mils of water with 5 drops acetic acid should give no precipitate on the addition of an equal bulk of hydrogen sulphide solution. Trade Varieties. Commercial manganese chloride is usually somewhat dis- coloured by various impurities chiefly iron. Such samples also show traces of sulphuric acid.