Far and away the most important element in flesh and bone is oxygen, and the bulk of that energetic gas which remains tranquilly compressed within us is something marvellous. In a ten-stone-ten man the weight of oxygen is no less than 106 lbs., and the natural bulk of it, if it were set free, would be equal to a beam of wood one foot square and 1,191 feet—nearly a quarter of a mile—long, or several hundred times the bulk of the body itself. Measured by the gallon it would fill 202 36-gallon barrels.
Even bulkier, though lighter, is the constituent hydrogen. Every man's body contains sufficient of this lightest of all substances to inflate a balloon that would lift himself, balloon, and tackle. In the ten-stone-ten man, for instance, the bulk of hydrogen is over 2,400 cubic feet—equal to the cubic space of a room ten feet high and 15½ feet square, and the weight of it is a trifle short of 13½ lbs.
Of that inexplicable gas, nitrogen, there is about half an ounce to each pound of body weight, or, approximately, 4½ lbs. altogether, in a 150 lb. man. It is about twenty times the bulk of the body, and by no means likes being cramped up in a space of a few cubic inches. This is the most inert gas known. Its bulk in the body is 58 cubic feet.
The reason it is said to be lifeless is that it hates every other element in the world; and, while oxygen, hydrogen, carbon, and the other things, like the Continental Powers, cannot live alone, nitrogen, like England, will not, if it can possibly avoid it, live in company. From this trait arises not only all the action of the human brain and the strength of the muscles, but the terrible force of all the great explosives. While individually without any energy whatever, when it does chance to enter into union with other things nitrogen becomes the most energetic substance in existence.
The great explosive force of nitroglycerine is due to azote. One of the most frightful explosives known is chloride of nitrogen, which goes off if the sun shines on it, or if a leaf touches it; and, in the human body, it is the breaking down of nitrogen compounds which actually constitutes life. Nothing can be alive without nitrogen, itself the type of death.
The last of the substances of any bulk in the body is carbon. There is, as nearly as possible, a sack of 21½ lbs. in a ten-stone-ten man, sufficient to make some sixty-five gross of lead pencils, sixty-five times as many as represented in our picture. It is veritably the fuel of the body, which both keeps us warm and gives us energy to move.
FIVE TACKS LIKE THESE CAN BE MADE FROM THE 48 GRAINS OF IRON IN THE BODY.
Thus it is the mainspring of animal life, which consists altogether of moving and keeping the body warm; the entire mechanism of the body, eyes to see, mouth and hands to grasp, stomach to digest, heart to circulate, and lungs to supply air, being designed to effect these two simple operations.
Although the above four elements form between 145 and 146 of a man's 150 lbs. of blood, flesh, and bone, the few pounds of the remaining elements are absolutely essential.