Schweitzer's Reagent

SCHWEITZER'S REAGENT (Ammoniacal cupric-oxide)

A solution of ammonia and copper oxide used for many tests. When cotton is placed in this solution the fibres swell and then dissolve. The reagent is of a deep blue colour. The action of this chemical on cotton is utilised in the manufacture of cuprammonium rayon. Cross and Bevan prepared it as follows : - 5 gramms copper sulphate are dissolved in 100 cc. of water. Hydrated copper oxide is precipitated from this solution by adding a slight excess of sodium hydroxide. The precipitate is washed entirely free from alkali, drained, and mixed with a 10 per cent solution of glycerol. The reagent is kept in stoppered bottles and when required for use is washed free from glycerol and dissolved in ammonia water of 20 per cent strength.