148 HUMAN HAIR 



more important matter than a single hair. 

 Suppose out of mere curiosity we look more 

 closely at some of the properties and the 

 composition of a hair. 



First, then, the hair has considerable elas- 

 ticity. 'It will stretch -33 of its length. It 

 has great powers of cohesion, for a single 

 healthy hair will carry from 3 to 5 Ibs. It 

 will resist putrefaction for a long time. There 

 are many proofs of this remarkable property. 

 It is highly hygroscopic,' * as it readily 

 detects damp in the atmosphere. It is also 

 capable of displaying electrical effects in dry, 

 frosty weather. Ladies know this when brush- 

 ing the hair. In some of the lower animals 

 hairs possess an additional property; they are 

 feelers and real organs of touch. 



1 As regards the chemical composition of 

 hair, it contains alkaline sulphates, calcium 

 sulphates, iron oxide, and salicic acid. Dark 

 hairs yield more iron than blonde hairs. The 

 black or brown colour of hair in general is due 



* Text-Book of Human Physiology. Landois and Stirling. 

 (C. Griffin & Co.) 



