3. Hydrolysis:
(a) loss of weight after boiling the raw fibre with a 1% caustic soda solution for five minutes;
(b) loss after boiling for one hour.
4. Determination of cellulose: the white residue after
(a) boiling for five minutes with 1% caustic soda,
(b) exposure to chlorine gas for one hour,
(c) boiling with basic sodium sulphite solution.
5. Mercerizing: the loss of weight after digestion with a 20% solution of sodium hydrate for one hour in the cold.
6. Nitration: the weight of the product obtained after digestion with a mixture of equal volumes of sulphuric and nitric acids for one hour in the cold.
7. Acid purification: treatment of the raw fibre with 20% acetic acid for one minute, the product being washed with water and alcohol, and then dried.