The ammonia is easily detected by its smell of hartshorn
and the blue colour produced on a piece of reddened litmus paper, the
latter being a general test to distinguish alkalis, like ammonia, soda,
and potash, from acids. No vegetable fibres will, under any
circumstances, give off ammonia. It may be asked, "But what does the
production of ammonia prove?" I reply, the "backbone," chemically
speaking, of ammonia is nitrogen. Ammonia is a compound of nitrogen and
hydrogen, and is formulated NH_{3}, and hence to discover ammonia in the
products as mentioned is to prove the prior existence of its nitrogen in
the wool, fur, and hair fibres.
_Action of Acids on Wool, etc._--Dilute solutions of vitriol (sulphuric
acid) or hydrochloric acid (muriatic acid, spirits of salt) have little
effect on wool, whether warm or cold, except to open out the scales and
confer roughness on the fibre. Used in the concentrated state, however,
the wool or fur would soon be disintegrated and ruined. But under all
circumstances the action is far less than on cotton, which is destroyed
at once and completely.
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