BS 3584:1989 pdf download.Determination of solubility of wool in urea-bisulphite solution.
2 Principle
A test specimen is immersed in a solution containing urea and disodium disulphite (also
known as sodium meta-bisulphite) of known concentration and specified composition, under
specified conditions of time, temperature and volume. The loss in mass is determined as the
difference between the dry masses of the test specimen before and after treatment.
3 Reagents
NOTE All reagents should be of analytical reagent quality.
3.1 Urea-bisulphite solution, freshly prepared on day of use, containing 50 g of urea, 3 g of disodium disulphite and 2 mL of 5 mol/L sodium hydroxide per 100 mL.
Dissolve the urea in boiling water, add the disodium disulphite, cool, add 2 mL sodium hydroxide
solution and make-up to volume. Check the pH value using a glass electrode pH meter and adjust to 7.0 ± 0.1 if necessary.
3.2 Urea solution, containing 25 g urea per 100 mL. Dissolve 250 g urea in 1 000 mL of water.
3.3 Water, complying with grade 3 of BS 3978.
3.4 Petroleum spirit, boiling range 40 °C to 60 °C.
4 Apparatus
4.1 Soxhlet extraction apparatus complying with BS 2071.
4.2 Water bath, or other means for controlling the temperature of the flask and contents at 65 ± 0.50 °C.
4.3 Conical flasks, 250 mL capacity, fitted with stoppers.
4.4 Sintered-glass filter crucibles, 30 mL capacity, of porosity P 160 in accordance with BS 1752.
NOTE If possible, these crucibles should have ground glass stoppers
4.5 Filter-flask, filter-pump and adaptor
4.6 Ventilated oven, for drying specimens at 105 ± 30 °C.
4.7 Stoppered weighing bottles
4.8 Balance, accurate to ± 0.0002 g
4.9 Desiccator.
5 Test specimens Take a sample representative of the bulk and not less than 10 g sufficient to provide wool for the following test specimens: a) one test specimen weighing approximately 1 g for determining the dry mass (see 6.2); b) two test specimens each weighing approximately 1 g for determining the solubility in urea-bisulphite (see 6.3). NOTE 1 If it is suspected that the sample contains acid (see 6.4) two further test specimens each weighing approximately 2 g may be taken from the sample for determining acid content by the method described in BS 6981. NOTE 2 Useful information on sampling is given in BS 2545. NOTE 3 The precision of results may be quite high given a very uniform sample, but, for example, in testing dyed loose wool the variations within the batch could be ± 2 % or more and fresh test specimens may be needed.
6 Procedure 6.1 Preparation of sample Extract the sample in the Soxhlet extraction apparatus (4.1) using petroleum spirit (3.4) for 1 h at a minimum rate of six cycles per hour. Allow the petroleum spirit to evaporate and then remove all vegetable and other obvious foreign matter. Disintegrate the sample into short lengths of approximately 10 mm and allow them to come to equilibrium with the laboratory atmosphere.BS 3584 pdf download.