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.

    19/180 (page 3)
    Clean the wire by holding it in the flame until all trace of the yellow coloration disappears. Then wash it in dilute HC1 and again heat it. (2) Take some baryta (or any barium salt) and heat it in the same way. The flame is of a yellowish-green colour, but possibly not very intense. Pour a few drops of HC1 into a watch-glass, dip the loop of the wire in it, and take up with the moistened wire a few particles of the salt. On now placing the wire in the flame, the yellowish-green coloration will be much more intense. Now clean the wire by alternately dipping it in HC1 and heating it in the flame. Por a time the effect of this is merely to increase the in* tensity of the coloration, but after some time it becomes fainter, and by using fresh acid once or twice the wire can be thoroughly cleaned. Barium compounds are the most difficult to remove from the wire. (3) Take some strontium nitrate and treat in the way described above. The flame is coloured an intense crimson \ moistening with HC1 makes the flame more intense. Clean the wire, wash it and put it away in a corked test tube or bottle. Borax bead reactions.—Fused borax possesses the power of dissolving many metallic oxides and salts with formation of compounds which often possess distinctive colours, and so afford valuable tests. (1) Take a piece of platinum wire fitted with a glass handle as already described, but without a loop at the end; heat in the Bunsen flame, and dip into powdered borax. Some of the salt will adhere to the wire. Again heat the wire, when the borax upon it will first “ intumesce,” i.e., swell up from the escape of its water of crystallization, and then fuse quietly to a clear, colourless bead. Now take a small quantity of a manganese compound e.g., MnS04 or Mn02, and bring it into contact with the bead, and again heat in the outer part of the Bunsen flame ; a charac¬ teristic purple or amethyst colour will be produced. If now the airholes at the base of the lamp be partially closed, so as to produce a slight luminous appearance in the upper