EPIDERMIS. C 299 



which continues till the portion of cuticle thus affected comes off, 

 a new portion being formed under it 



It is very easily dissolved in the caustic alkalies, even when 

 very dilute. The alkaline carbonates do not attack it. The 

 alkaline sulphurets give it a dark-brown almost black co- 

 lour, and the stain is not removed until the cuticle is renewed. 

 The chloride of gold tinges it purple. Nitrate of silver stains it 

 a chalky white, which on exposure to the light becomes gradu- 

 ally black. If the recent stain before becoming black be wash- 

 ed with caustic ammonia, the greatest part of the silver may be 

 removed. Parabanic acid and several other preparations from 

 uric acid stain it of a beautiful crimson colour. 



Mr Hatchett has drawn as a conclusion from the characters of 

 the epidermis that it is quite analogous in its nature to coagulat- 

 ed albumen. How far this conjecture is correct can only be de- 

 termined by an ultimate analysis. 



According to John,* the epidermis of the foot is composed of, 



Indurated albumen, . 93 to 95 



Mucus with trace of animal matter, 5 



Lactic acid, 



Lactate of potash, 



Phosphate of potash, 



Chloride of potassium, 



Sulphate of lime, 



Ammoniacal salt, 



Phosphate of lime, 



Manganese ? and iron 



Soft fat, . . . 0-08 



The epidermis of a woman affected with herpes was composed 

 of, 



Indurated albumen, . 92 to 93 



Mucus, . . 7 to 6 



Lactic acid and the above stated salts, . 1 

 Soft fat, . 0-75 to 1 



Dr Scherer subjected to analysis a portion of the epidermis 

 of the sole of the footf It was well washed with water, and then 

 boiled in alcohol and ether. When burnt it left one per cent, of 

 ashes. Abstracting the ashes its constituents were, 



* Annals of Philosophy, ix. 55. f Ann - der Pharm. xl. 54. 



