\4iQ ON UUMAN HAIR, 



vre must suppose, that.in these critical moments, when 

 nature undergoes a reyolution, and the natural functions 

 are in consequence suspended or changed, some agent is 

 developed in the animal economy, which, passing into 

 the hair, decomposes the colouring matter. But what 



owing to an agent can produce this effect ? The acids alone appear 

 capable of it: at least this is certain, black hair immersed 

 some time in them, particularly in the oxigenated muri- 

 atic acid, whitens very evidently. 



Arguments in The rapid production of an acid in the animal economy 



oDin?on.° ^^ ^^^^ ^^^ appear to him impossible, considering that a fit 

 of anger in men, as well as in inferior animals, is sufficient 

 to change the nature of certain of their fluids, and render 

 them venomous; and seeing that the galvanic fluid fre- 

 quently occasions the formation of an acid or an alkali, 

 according to circumstances, both in animal and vegetable 



"Whiteness substances. As to the whiteness produced gradually by 



from age. ^^^^ j^^ ascribes this to a deflcient secretion of colouring 



matter. 



Properties ow- In hair, exclusive of the animal matter that forms its 



louring matter" ^^^^^5 ^"^ which is the same in all, there is a colouring 

 matter, that may be separated from it, and the hue of 

 which varies according to the kind of hair of which it 

 constitutes the distinction. To this fatty substance Mr, 

 Vauquelin attributes the suppleness, elasticity, and un- 

 alterability, which exist in hair : to this substance too is 

 owing no doubt the property it has of burning so rapidly, 

 and that of forming soap abundantly with alkalis. 



Its animal sub- After having treated of the colouring matters of hair, 

 he endeavours to characterise the animal matter, that forms 

 its substance, by comparing it with all those of which 

 we have any knowledge. Without relating all the expe-- 

 riments he has made in this respect, we shall observe, that 



Is neither gcla- j^ jg ^^^^ gelatine, since its solution in water, which is 

 * difficult to effect, never becomes a jelly on evaporation ; 



Bor albumen; neither is it albumen, for this would not dissolve in boil- 

 ing water without being decomposed, and its solution 

 would be differently affected by reagents. 



but mucus, or The humour to which the substance of hair approaches 



8omethin_g si- ^g^^est, if it bc not absolutely the same, is, according to 



Mr. Vauquelin, that which physiologists have designated 



