Bacons Modification of Stepanoffs Method

The sodium halide can be separated and estimated either volumetrically or gravimetrically by recognised methods. 

The amount of reactants employed depends on the halogen present. For a weight W of substance the. following relationships approximately hold — 

Piria and Schiff s Method.—This method is only applicable to those organic substances which are not highly volatile. Liquids which combine directly with CaO or Na2C03 may also be analysed in this way. 

About 0 1—0-3 gm. of the substance is weighed into a very small platinum crucible, which is then filled up with an intimate mixture of anhydrous Na COs (1 part) and pure powdered CaO (4—5 parts). The crucible is then placed in an inverted position in a larger platinum crucible, the space between the two being completely filled with the same mixture of NagC03 and CaO, so that the small crucible is entirely covered. 

The outer crucible is now heated in a large Bunsen or blowpipe flame so that the outer portions attain a high temperature before the substance in the smaller crucible begins to decompose. The whole is finally raised to a red heat. The crucibles and contents are allowed to cool, then digested with water in a strong beaker. Dilute HN03 is cautiously added 

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