THE SKIN AND HAIR. 83 



touch of sulphuretted hydrogen gas. The solution, having 

 found its way into each filament of hair by absorption, there 

 remains ; and subsequently, the gas during evolution coming 

 into contact with it, change of colour to darkness results. 

 Long before the theory of this action was understood, leaden 

 combs had acquired a celebrity for the change of colour they 

 effected on red hair after continuous use. It is not that the 

 stain of abraded lead is so black, it is more lustrously metallic. 

 But for the hydrosulphuric acid gas evolved sulphuretted 

 hydrogen the use of leaden combs would not be efficient. 

 The explanation of their utility has already been set forth. 

 First, the small particles of abraded lead the actual lead 

 stain coming into contact with certain acids present natu- 

 rally amidst the hair-filaments, is dissolved. Being dissolved 

 it is soon absorbed, when the sulphuretted hydrogen taking 

 effect produces blackness. The change effected by a leaden 

 comb, however, is very slow, the operation needing to be per- 

 formed again and again before any result is apparent. Hence 

 in process of time a readier mode of operation was devised, 

 having reference to the same theory. It was found that a 

 mixture of litharge, or oxide of lead, and lime, made into a 

 paste with water, furnished a convenient means of effecting 

 the dyeing rapidly. It was seen that if hair were daubed 

 with the paste over-night, and secured in an oilskin bag to 

 retain the blackening gas, then next morning, on brushing 

 away the powder and pomading, the hair would be found to 

 be black. I am told that the discovery of this mode of treat- 

 ment was made by some British military horse-doctor, whose 

 name has been lost in the efflux of time. This is a pity, 

 seeing that the discovery is ingenious, and does him credit. 



I am informed that many of the horses on which our 

 household troops are mounted, notwithstanding the immacu- 

 late beauty of their lustrous black coats, are very prone to 

 have tails of less unimpeachable jet. Wherefore again, I am 

 told, tire practice still prevails of daubing these defective tails 



