36 SIMPLE CHEMICAL ELEMENTS. 



ever, not been confirmed; and either of these three substances, found 

 in the human organism, must be regarded as accidentally present. 

 Iodine and bromine enter into the composition of the lowest marine 

 animals ; but it is not yet proved, nor probable, that they normally 

 form a part of the human body, though such an assertion has been 

 made. 



The fifteen elements just mentioned unite variously to form the 

 immediate principles of the tissues hereafter to be considered. The 

 following is, however, a general account of the parts and the fluids 

 in which each is found : 



1-4. The first four elements are found in all the tissues, and most 

 of the fluids, except fat ; the first three in all tissues and fluids, 

 without exception. Of the first two water is constituted; whose 

 abundance in the human organism has already been alluded to. 



5, 6. Sulphur and phosphorus exist in the albuminous group of 

 immediate principles (albumen, fibrine, &c.), and in the tissues formed 

 from them, and all animal cells. They also enter largely into the 

 composition of the brain about T 4 of its weight being phospho- 

 rus. ( Von Bibra.) Sulphur is a constituent of hair and nails, which 

 accounts for their odor during combustion. Both the sulphuric and 

 the phosphoric acids exist in the urine, and the latter in bones also, 

 in combination with lime and magnesia. Treviranus believed that 

 spontaneous combustion of the human body may be due to an ex- 

 cess of phosphorus in it. 



7, 8. Calcium and magnesium are found only in the state of 

 oxides, i.e. as lime and magnesia; and combined with acids to form, 

 salts. The phosphate of lime constitutes about one-half the weight 

 of human bone, and the carbonate about one-tenth ; the phosphate 

 of magnesia amounts to the one-hundredth part. Both these ele- 

 ments also exist in milk, and other fluids. 



9. Sodium, in combination with chlorine i. e. forming common 

 salt exists in every solid and fluid in the body. In all other cases 

 it is in the form of an oxide (soda), and, in combination with acids, 

 forms various salts in the different tissues and fluids. 



10. Potassium also unites with chlorine to form the chloride of 

 potassium, the latter being abundant in muscular tissue. Otherwise 

 it is in the oxide state potassa and in combination with acids. It, 

 however, exists but sparingly in animals, in comparison with soda, 

 while it abounds in plants. 



11. Chlorine combines with hydrogen to form the hydrochloric 



