and Observations on the component Parts of Membrane. 371 



it became a brittle substance, which was easily reduced to a 

 powder. 



Hair was much less affected than either of the abovementioned 

 substances; and this, with others in some measure similar, I 

 shall now more particularly notice. 



The substances to which I allude, are hair, feather, horn, 

 horny scale, hoof, nail, and the horn-like crust which covers 

 some insects and other animals, such as the scorpion and the 

 tortoise. These I shall now mention, in as concise a manner as 

 the subject will allow. 



When hair of various qualities, and taken from different 

 animals, was long digested or boiled with distilled water, it 

 imparted to the water a small portion of gelatin, which was 

 precipitated by the tanning principle, and by nitro-muriate of 

 tin ; and, when the hair had been thus deprived of gelatin, and 

 was subsequently dried in the air, the original flexibility and 

 elasticity of it was found to be much diminished, so that it 

 easily gave way, and was broken. 



This effect, Mr. Achard has also noticed ; * and I am in- 

 duced to believe (from various experiments which I have made 

 on these substances) that the hair which loses its curl in moist 

 weather, and which is the softest and most flexible, is that 

 which most readily yields gelatin ; and, on the contrary, the 

 hair which is very strong and elastic, is that which affords it 

 with the greatest difficulty, and in the smallest proportion. 



These remarks have moreover been corroborated, by the 



* " La perte de la partie gelatineuse otanr aux cheveux leur souplesse, il s'ensuit 

 " que c'est aux parties gelatineuses qui entrent dans la composition des cheveux qu'ils . 

 " doivent leur pliant et leur elasticke." — Examen cbimique des Cbevex. ££<?„ 

 Memoires de I' Acad, de Berlin. Tom. XXXVIII. p. 12 



