Division VARIANT No 4

Consider the case of a fibre mixture which when qualitatively analysed gave the following components: carded wool, viscose, unbleached cotton.

Suppose that using variant 4, that is successively removing two components from the mixture of one single specimen, the following results are obtained:

1. 1..

   Dry mass of the specimen after pre-treatment (m) = 1,6000 g

2. 2..

   Dry mass of the residue after treatment with alkaline sodium hypochlorite (viscose + cotton) (r₁) = 1,4166 g

3. 3..

   Dry mass of the residue after the second treatment of the residue r₁ with zinc chloride/formic acid (cotton) (r₂) = 0,6630 g

Treatment with alkaline sodium hypochlorite does not entail any loss in mass of viscose, while unbleached cotton loses 3 %, therefore d₁ =1,00 and d₂ = 1,03.

As a result of treatment with formic acid-zinc chloride, the mass of cotton increases by 4 %, so that d₃ = 1,03 × 0,96 = 0,9888, rounded to 0,99, (d₃ being the correction factor for the respective loss or increase in mass of the third component in the first and second reagents).

If the values obtained by chemical analysis and the correction factors are substituted in the formulae given in I.8.1.4, the following result is obtained:

P₂% (viscose) = 1,00 × (1,4166/1,6000) × 100 – (1,00/1,03) × 41,02 = 48,71 %

P₃% (cotton) = 0,99 × (0,6630/1,6000) × 100 = 41,02 %

P₁% (wool) = 100 – (48,71 + 41,02) = 10,27 %

As has already been indicated for Variant 1, these percentages must be corrected by the formulae indicated in point I.8.2.

P₁A% (wool) = 10,27 × [1 + (17,0 + 0,0)/100)]/[10,27 × (1 + (17,00 + 0,0)/100) +48,71 × (1 + (13 + 0,0)/100) + 41,02 × (1 + (8,5 + 4,0)/100)] × 100 = 10,61 %

P₂A% (viscose) = 48,71 × [1 + (13 + 0,0)/100] / 113,2057 × 100 = 48,62 %

P₃A% (cotton) = 100 – (10,61 + 48,62) = 40,77 %

The raw material composition of the mixture is therefore as follows: