INCRUSTATIONS. 483 



phate of soda. The portion insoluble in water appeared, when 

 examined under the microscope, to consist of epithelium- cells, 

 for the most part more or less injured. Alcohol took up from 

 these scales a little yellow fat which partly separated on cooling : 

 this portion consisted of margaric acid and margarin, while 

 oleic acid remained in solution. The ash left by the direct in- 

 cineration of the scales contained scarcely appreciable traces of 

 sulphates or chlorides, a little carbonate and a large amount of 

 phosphate of soda, earthy phosphates, and a trace of iron. 

 Hence these scales contained the ordinary fats and fatty acids, a 

 little uncoagulated albumen, a large quantity of albuminate of 

 soda, some extract of flesh, and a considerable amount of salts, 

 in which the phosphate of soda and earthy phosphates predo- 

 minated. No bilin could be detected, and only a trace of bile- 

 pigment. 



I have recently examined the scales of a person with 

 ichthyosis. They were of a gray or black colour ; when placed 

 in water they softened, and on then placing a section under the 

 microscope I found that the abnormal structure was formed of 

 compressed epithelium-scales. 



On incineration the scales left an ash containing carbonate 

 and phosphate of lime, and peroxide of iron ; the latter was in 

 such abundance as to communicate a yellow colour to the ash, 

 The ash yielded by the incineration of the ordinary thickened 

 skin on the hands and feet is perfectly white, and contains a 

 mere trace of peroxide of iron. 



