atment. In examining one of these fibres from the side of a hare, you
see what the cause of this roughness is, and what is also the cause of
the difficulty in giving a polish or finish. The free edges are
partially disintegrated, etched as it were, besides being caused to
stand out. A weaker acid ought to be used, or more mercury and less
acid. As we shall afterwards see, another dangerous agent, if not
carefully used, is bichrome (bichromate of potassium), which is also
liable to roughen and injure the fibre, and thus interfere with the
final production of a good finish.

LECTURE II

TEXTILE FIBRES, PRINCIPALLY WOOL, FUR, AND HAIR--_Continued_

With regard to the preparation of fur by acid mixtures for felting,
mentioned in the last lecture, I will tell you what I think I should
recommend. In all wool and fur there is a certain amount of grease, and
this may vary in different parts of the material. Where there is most,
however, the acid, nitric acid, or nitric acid solution of nitrate of
mercury, will wet, and so act on the fur, least. But the action ought to
be uniform, and I feel sure it cannot be until the grease is removed. I
should therefore first wash the felts on the fur side with a weak
alkaline solution, one of carbonate of soda, free from any caustic, to
remove all grease, then with water to remove alkali; and my belief is
that a weaker and less acid solution of nitric acid and nitrate of
mercury, and a smaller quantity of it, would then do the work required,
and do it more uniformly.

A question frequently asked is: "Why will dead wool not felt?" Answer:
If the animal become weak and diseased, the wool suffers degradation;
also, with improvement in health follows _pari passu_, improvement in
the wool structure, which means increase both in number and vigour of
the scales on the wool fibres, increase of the serrated ends of these,
and of their regularity. In weakness and disease the number of scales in
a given hair-shaft diminishes, and these become finer and less
pronounced. The fibres themselves also become attenuated. Hence when
disease becomes death, we have considerably degraded fibres. This is
seen clearly in the subjoined figures (see Fig. 13), which are of wool
fibres from animals that have died of disease. The fibres are attenuated
and irregular, the scale markings and edges have almost disappeared in
some places, and are generally scanty and meagre in development. It is
no wonder that su