THE SKIN AND HAIR. 89 



inapplicable to hair naturally dark until some preliminary 

 bleaching has been adopted. Several fluids have the property 

 of bleaching hair. Alkaline solutions bleach it to a certain 

 extent ; solution of chlorine, and the so-called chlorides of 

 soda, and of lime, more effectually. Solution of sulphurous 

 acid will also bleach hair ; so will solutions of bisulphite of 

 magnesia and of lime ; peroxide of hydrogen has acquired 

 great celebrity under many imaginative names. Whatever 

 process be had recourse to, the subsequent operation of yellow- 

 tinting is prosecuted as already set forth. 



Copper solutions are sometimes used for imparting a tint 

 to fair hair not very unlike a tint sometimes seen in natural 

 beards and whiskers. To understand the rationale of this use, 

 we must again refer to our chemistry. If a copper solution 

 be tested with a solution of prussiate of potash (ferrocyanide 

 of potassium), a brown tint, condensing into a precipitate of 

 the same colour if the solution be strong, results. Solutions 

 of three other metals viz. titanium, uranium, and molybde- 

 num yield a similar tint under similar treatment ; but I am 

 not aware that either metal of the group save copper has been 

 ever employed as the basis of a hair-dye. Our ideal labora- 

 tory experiments have shown that the mordant, or second 

 application, must be solution of prussiate of potash. Hair 

 moistened with sulphate-of -copper solution first, and prussiate- 

 of -potash solution to follow immediately, turns brown ; as to 

 the precise tint of brown evolved, it is exactly that of old 

 Spanish mahogany. De gustibus non disputandum: the pro- 

 cess is easy ; let those who like use it. 



For the dyeing brown of small tufts of hair, such as 

 whiskers, moustachios, and imperials, solution of the chloride 

 of gold might be used, but I am not aware that it ever is used. 

 I have tried it experimentally, and find the result to be more 

 satisfactory than of most hair-dyes. Chloride of gold, how- 

 ever, has the disadvantage of acting as a substantive colour. 

 It needs no second application or mordant, and it dyes both 



