Qualitative analysis / by William Briggs and R.W. Stewart.

  • William Briggs
Date:
1913
Catalogue details

Licence: Public Domain Mark

Credit: Qualitative analysis / by William Briggs and R.W. Stewart. Source: Wellcome Collection.

    144/180 (page 128)
    Oxalate and Tartrate. To a neutral solution add calcium chloride; shake well and allow to stand for 20 minutes. Filter off the precipitate, which consists of calcium oxalate and tartrate. Wash well on the filter-paper. Remove a small portion of the precipitate for confirmatory tests C and D below. Make a hole in the filter-paper and wash residue through into a boiling tube. Boil with a little acetic acid. Filter. Filtrate. Evaporate just to dryness and heat with a little strong sulphuric acid. Carbon monoxide and diox- i ide, and sulphur dioxide evolved, vith immediate blackening. Presence of Tartaric Acid. Confirm as follows— C. Heat one portion of residue (see above) on a piece of porcelain, with strong sulphuric acid con¬ taining resorcin. Reddish-violet Coloration. D. Place second portion in a test- tube with a drop or two of am - i monia, a crystal of silver nitrate,! and a little water. Heat gently. Mirror of metallic silver produced. Residue = Calcium oxalate. Wash well and dry. Divide into two parts A and B. A. Place on a piece of platinum foil and heat over the Bunsen tiame to convert into calcium carbonate. Allow to cool, and add acetic acid. Carbon dioxide evolved with effervescence. Presence of Oxalic Acid confirmed. B. Heat in a test-tube with strong sulphuric acid. Carbon dioxide and monoxide evolved, without blackening. Presence of Oxalic Acid confirmed. Free Acids. [Only the following common acids are considered here - HC1, HNO3, H2S04, HoPQ4, H3B03, acetic acid, oxalic acid, tartaric acid, citric acid.] If you find on going through the groups that no base is * present, then— (1) If the substance is solid it may be one of the