The study of the cuticle of keratin fibers has led to an analysis of the proteins extracted by the formic acid used in separating the cuticle by ultrasound techniques. It was observed that there were differences in the glycine and tyrosine contents of wool and mohair extracts. This led to the development of a method of quantitative analysis for these fibers in a blend. The method is not yet universally applicable but can be used to analyze grey-state or dyed fabrics to an accuracy of ± 10%. -- AATA