INCIDENTAL. 3 



4. Carbonate of soda is a very common ingredient in the ash 

 of animal substances ; in most cases it is derived from com- 

 pounds of soda with organic acids, especially lactic acid. It 

 is also found in the urine of the graminivora. 



5. Phosphate of soda occurs in the blood, lymph, chyle, bile, 

 milk, and urine. Its formula is HO, 2 Na O, PO., + 24 HO. 

 On the addition of muriate of ammonia to a solution of this 

 salt, we obtain the " sal microcosmicus " of the older chemists, 

 which is found in considerable quantity in decomposed animal 

 fluids; its formula is HO, NH^ O, NaO, PO^ + 8 HO. The 

 recent investigations of Enderlin tend to prove that the phos- 

 phate of soda that most commonly occurs in the animal fluids 

 and tissues, contains 3 atoms of soda, and may be represented 

 by the formula 3 Na O, PO^. 



6. Chloride of calcium is found in the gastric juice and saliva. 



7. Chloride of iron (apparently the proto-salt) occurs in he 

 gastric juice. 



8. Iron is found in considerable quantity in hoematin, the prin- 

 cipal colouring matter of the blood ; also in lymph, chyle, black 

 pigment of the eye, hair, &c. In what state it exists, whether 

 as a peroxide or protoxide, or either, is not known. It is also 

 found in lesser proportion in bile, urine, sweat, milk, &c. In 

 some of these fluids it is stated to exist as a phosphate. 



CLASS III. INCIDENTAL CONSTITUENTS. 



1. Chloride of potassium is found in almost all the animal fluids. 



2. Alkaline sulphates occur in small quantity in most of the 

 animal fluids, in the blood, milk, urine, and sweat. Mitscherlich 

 could not detect any alkaline sulphates in the saliva, and 

 Lehmann has recently shown that they do not exist in the bile, 

 although they may be produced in the ash. 



3. Carbonate of magnesia has been found in alvine concre- 

 tions, urinary calculi, &c., in man and the mammalia. It 

 occurs in considerable quantity in the urine of the graminivora, 

 and is a constituent of the shell of the egg. Berzelius suggests 

 the probability of magnesia being contained in bone, not as a 

 phosphate but as a carbonate, and that the phosphate of mag- 

 nesia is produced during analysis. 



4. Manganese has been found in the hair ; it has also been 



