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.