APPENDIX. 343 



chemistry of the blood. Peroxide of iron is found, in very small quanti- 

 ties, in the ashes of bones, muscles, and many tissues, and in lymph and 

 chyle, albumin of serum, fibrin, bile, and other fluids; and a salt of iron, 

 probably a phosphate, exists in the hair, black pigment, and other deeply 

 colored epithelial or horny substances. 



Aluminium, Manganese, Copper, and Lead. It seems most 

 likely that in the human body, copper, manganesium, aluminium and 

 lead are merely accidental elements, which, being taken in minute quan- 

 tities with the food, and not excreted at once with the faeces, are absorbed 

 and deposited in some tissue or organ, of which, however, they forfci no 

 necessary part. In the same manner, arsenic, being absorbed, may be 

 deposited in the liver and other parts. 



