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 such “dead wool” will be badly adapted for felting.  “Dead wool” is nearly as bad as “kempy” wool, in which malformation of fibre has occurred.  In such “kemps,” as Dr. Bowman has shown, scales have disappeared, and the fibre has become, in part or whole, a dense, non-cellular structure, resisting dye-penetration and felting (see Fig. 14).

[Illustration:  FIG. 13.]

[Illustration:  FIG. 14.]

One of the physical properties of wool is its hygroscopicity or power of absorbing moisture.  As the very structure of wool and fur fibre would lead us to suppose, these substances are able to absorb a very considerable amount of water without appearing damp.  If exposed freely to the air in warm and dry weather, wool retains from 8 to 10 per cent., and if in a damp place for some time, it may absorb as much as from 30 to 50 per cent. of water:  Wool, fur, or hair that has been washed, absorbs the most moisture; indeed, the amount of water taken up varies inversely with the fatty or oily matter present.  Hence the less fat the more moisture.  In the washed wool, those fibres in which the cells are more loosely arranged have the greatest absorbing power for water.  No doubt the moisture finds its way in between the cells of the wool fibre from which the oil or fat has been removed.  But I need hardly remind you that if wool and fur are capable, according to the circumstances under which they are placed, of absorbing so much moisture as that indicated, it becomes (especially in times of pressure and competition) very important to inquire if it be not worth while to cease paying wool and fur prices for mere water.  This question was answered long ago in the negative by our Continental neighbours, and in Germany, France, and Switzerland official conditioning establishments have been founded by the Governments of those countries for the purpose of testing lots of purchased wool and silk, etc., for moisture, in order that this moisture may be deducted from the invoices, and cash paid for real dry wool,