The Reason Why. Robert Kemp Philp

which it is found in the atmosphere, would be too exciting to the animal system. Animals placed in pure oxygen die in great agony from fever and excitement, amounting to madness.

      "As vinegar is to the teeth, and as smoke to the eyes, so is the sluggard to him that sent him."—Proverbs x.

33. What is nitrogen?

      Nitrogen is an elementary body in the form of gas.

34. Where is nitrogen found?

      It is chiefly found in the air, of which it constitutes 79 out of 100 volumes. It may be mixed with oxygen in various proportions; but in the atmosphere it is uniformly diffused. It is found in most animal matter, except fat and bone. It is not a constituent of the vegetable acids, but it is found in most of the vegetable alkalies.

      35. What are acids?

      Acids are a numerous class of chemical bodies. They are generally sour. Usually (though there are exceptions) they have a great affinity for water, and are easily soluble therein; they unite readily with most alkalies, and with the various oxides. All acids are compounds of two or more substances. Acids are found in all the kingdoms of nature.

36. What are alkalies?

      Alkalies are a numerous class of substances that have a great affinity for, and readily combine with, acids, forming salts. They exercise peculiar influence upon vegetable colours, turning blues green, and yellows reddish brown. But they will restore the colours of vegetable blues which have been reddened by acids; and, on the other hand, the acids restore vegetable colours that have been altered by the alkalies. Alkalies are found in all the kingdoms of nature.

37. Could animals live in nitrogen?

      No; they would immediately die. But a mixture of oxygen and nitrogen, in equal volumes, constitutes nitrous oxide, which gives a pleasurable excitement to those who inhale it, causing them to be merry, almost to insanity; it has, therefore, been called laughing gas.

38. Why does nitrous oxide produce this effect?

      Because it introduces into the body more oxygen than can be consumed. It, therefore, deranges the nervous system, and being a powerful stimulant, gives an unnatural activity to the nervous centres and the brain.

      "Lord, make me know mine end, and the measure of my days, that I may know how frail I am."—Psalm xxxix.

39. In what proportions are the atmospheric gases found in the blood?

      The mean quantity of the gases contained in the human blood has been found to be equal to 1–10th of its whole volume. In venous blood, the average quantity of carbonic acid is about 1–18th, that of oxygen about 1–85th, and that of nitrogen about 1–100th of the volume of the blood. In arterial blood their quantities have been found to be carbonic acid about 1–14th, oxygen about 1–38th, and nitrogen about 1–72nd.

40. Then is nitrogen taken into the blood from the air?

      Such a supposition is highly improbable. It is probably derived from nitrogenised food, just as carbonic acid is derived from carbonised food.

41. What is venous blood?

      Venous blood is that which is returning through the veins of the body from the organs to which it has been circulated.

42. What is arterial blood?

      Arterial blood is that which is flowing from the heart through the arteries to nourish the parts where those arteries are distributed.

      43. What is the difference between venous and arterial blood?

      Venous blood contains more carbonic acid, and less oxygen and nitrogen than arterial blood.

44. Will nitrogen burn?

      It will not burn, nor will it support combustion.

45. What is the difference between "burning" and "supporting combustion?"

      Oxygen gas will not burn of itself, but it aids the decomposition by fire of bodies that are combustible. It is therefore called a supporter of combustion. But hydrogen gas, though it burns of itself will extinguish a flame immersed in it. It is therefore said to be a body which will burn, but will not support combustion.

      "As coals are to burning coals, and wood to fire; so is a contentious man to kindle strife."—Proverbs xxvi.

46. What becomes of the nitrogen that is inhaled with the air?

      It is thrown off with the breath, mixed with carbonic acid gas, and flies away to be renewed by a fresh supply of oxygen.

47. Where does nitrogen find a fresh supply of oxygen?

      In the atmosphere. Nitrogen is said to possess a remarkable tendency to mix with oxygen, without having a positive chemical affinity for it. That is to say, neither the oxygen nor the nitrogen undergoes any change by the union, except that of admixture. The oxygen and the nitrogen still possess their own peculiar properties. Oxygen and nitrogen are found in nearly the same proportions in all climates, and at all altitudes.

48. In combustion does any other result take place besides the union of oxygen and carbon forming carbonic acid gas?

      Yes. Usually hydrogen is present, which in burning unites with oxygen, and forms water.

CHAPTER IV.

       Table of Contents

      49. What is hydrogen?

      Hydrogen is an elementary gas, and is the lightest of all known bodies.

50. Will hydrogen support animal life?

      It will not. It proves speedily fatal to animals.

51. Will hydrogen support combustion?

      Although it will burn, yielding a feeble bluish light, it will, if pure, extinguish a flame that may be immersed in it. Hydrogen will therefore burn, but will not support combustion.

52. Why will hydrogen explode, if it will not support combustion?

      When hydrogen explodes it is always in combination with oxygen, or with the common air, which contains oxygen. Two measures of hydrogen and one of oxygen form a most explosive compound.

      "As smoke is driven away, so drive them away: as wax melteth before the fire, so let the wicked perish at the presence of God."—Psalm xlvi.

      53. Why does hydrogen explode, when mixed with oxygen, upon being brought in contact with fire?

      Because of its strong affinity for oxygen, with which, upon the application of heat, it unites to form water.

54. Where does hydrogen chiefly exist?

      In the form of water, where it exists in combination with oxygen. Eleven parts of hydrogen, and eighty-nine of oxygen, form water.

      55. Is hydrogen found elsewhere?

      It is never found but in a state of combination; united with oxygen, it exists in water; with nitrogen, in ammonia; with chlorine, in hydro-chloric acid; with fluorine, in hydro-fluoric acid; and in numerous other combinations.

56. Is the