34 HISTOLOGY. 



of others, which, although they exist in smaller proportions, still form im- 

 portant constituents of peculiar tissues. Thus we find 



Lime, or its base, calcium, combined with the carbonic or phosphoric 

 acids, in the bones and teeth. 



Magnesia, in the sebaceous matter of the skin. 



JHumina, in the enamel of the teeth ; 



And iron, in the black pigment in various parts. 



The additional elements thus brought into the organism may be enume- 

 rated as follows : 



Metallic bases of earths. Calcium, magnesium, silicium, aluminum. 

 Metallic bases of alkalies. Potassium, sodium. 

 Phosphorus, sulphur, chlorine, and fluorine. 

 Metals. Iron, manganese, titanium, arsenic, and copper. 

 Almost all of these elements exist compounded in either the binary or 

 ternary form. 



The binary compounds are 



Water, found universally consisting of 1JO. 

 Carbonic acid, found in blood, urine, sweat. 



Carbonates, or salts of carbonic acid : 



Carbonate of soda, in serum, bile, mucus, sweat, saliva, tears, carti- 

 lage, &c. 



Carbonate of ammonia, in the amniotic liquor, probably derived from 

 the urine of the foetus. 



Carbonate of lime, in cartilage, bone, and the teeth. 



Carbonate of magnesia, in the sebaceous matter of the skin. 



Salts of phosphoric acid : 



Phosphate of soda, in serum, saliva, sweat, bones, muscles, &c. 



Phosphate of lime, in bones, teeth, cartilage, and the sandy concretions 

 ot the pineal gland. 



Phosphate of soda and ammonia, in urine and blood; but probably only 

 for the purpose of being excreted or thrown off as unfit to constitute a 

 part of an animal body. 



Phosphate of iron, in blood, gastric juice, and urine. 



Chlorine and its compounds : 



Hydrochloric add, in gastric juice, and in the fluid of the caecum. 

 Chloride of sodium, in blood, brain, muscle, bone, cartilage, dentine, 

 end pigment. 



Chloride of potassium, in blood, gastric juice, milk, saliva. 

 Chloride of ammonium, in sweat, gastric juice. 

 Chloride of calcium, in gastric juice. 



Sulphuric acid and its compounds : 



Sulphate ofpotassa, in urine, gastric juice, and cartilage. 



Sulphate of soda, in sweat, bile, and cartilage. 



Sulphate of lime, in bile, hair, and cuticle. 



Sulpho-cyanide ofpotassa, in the saliva. 



Fluoride of calcium, in the enamel. 



'Silica and oxide of manganese, in the hair. 



Mumma, in the enamel. 



