ISO 1833-15:2019

This document specifies a method, by determining the nitrogen content, to calculate the proportion of each component, after the removal of non-fibrous matter, in textiles made of mixtures of
-  jute
with
-  animal fibres.
The animal-fibre component can consist solely of hair or wool, or of any mixtures of the two.
This document is not applicable to products in which dyestuffs or finishes contain nitrogen.
NOTE    Because this method differs in principle from the general method based on selective solubility set out in ISO 1833-1, it is given in a form that is complete in itself.