ium combined with oxygen) is contained in the hair and
in some of the secretions.

49. IRON forms the coloring principle of the red globules of the
blood, and is found in every part of the system.

_Observation._ As metallic or mineral substances enter into the
ultimate elements of the body, the assertion that all minerals are
poisonous, however small the quantity, is untrue.

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42. What is an ultimate element? Give examples. 43. How are they
divided? Name the metallic substances. Name the non-metallic
substances. 44. What is said of potash? 45. Of soda? 46. Of lime? 47.
Of magnesia? 48. Of silex? 49. What forms the coloring principle of
the blood? What is said of mineral substances?

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50. OXYGEN is contained in all the fluids and solids of the body. It
is almost entirely derived from the inspired air and water. It is
expelled in the form of carbonic acid and water from the lungs and
skin. It is likewise removed in the other secretions.

51. HYDROGEN is found in all the fluids and in all the solids of
the body. It is derived from the food, as well as from water and
other drinks. It exists in the greatest abundance in the impure,
dark-colored blood of the system. It is removed by the agency of the
kidneys, skin, lungs, and other excretory organs.

52. CARBON is an element in the oil, fat, albumen, fibrin, gelatin,
bile, and mucus. This element likewise exists in the impure blood in
the form of carbonic acid gas. Carbon is obtained from the food, and
discharged from the system by the secretions and respiration.

53. NITROGEN is contained in most animal matter, but is most abundant
in fibrin. It is not contained in fat and a few other substances.

_Observation._ The peculiar smell of animal matter when burning is
owing to nitrogen. This element combined with hydrogen forms
_am-mo'ni-a_, (hartshorn,) when animal matter is in a state of
putrefaction.

54. PHOSPHORUS is contained in many parts of the system, but more
particularly in the bones. It is generally found in combination with
oxygen, forming _phosphoric acid_. The phosphoric acid is usually
combined with alkaline bases; as lime in the bones, forming phosphate
of lime.

55. SULPHUR exists in the bones, muscles, hair, and nails. It is
expelled from the system by the skin and intestines.

56. CHLORINE is found in the blood, gastric juice, milk, perspiration,
and saliva.

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