“We only know the fact that there are some things that will absorb gases—suck them in—make them disappear. Charcoal will, for instance. It is thought that the iron which the blood contains gives it the curious property of absorbing oxygen. Well; the oxygen going into the blood makes it change from dark to bright scarlet; and then this blood containing oxygen is conveyed all over the system by the arteries, and yields up the oxygen to combine with hydrogen and carbon as it goes along. The carbon and hydrogen are part of the substance of the body. The bright scarlet blood mixes oxygen with them, which burns them, in fact; that is, makes them into carbonic acid and water. Of course, the body would soon be consumed if this were all that the blood does. But while it mixes oxygen with the old substance of the body, to burn it up, it lays down fresh material to replace the loss. So our bodies are continually changing throughout, though they seem to us always the same; but then, you know, a river appears the same from year’s end to year’s end, although the water in it is different every day.” “Eh, then,” said Mr. Bagges, “if the body is always on the change in this way, we must have had several bodies in the course of our lives, by the time we are old.” “Yes, uncle; therefore, how foolish it is to spend money upon funerals. What becomes of all the bodies we use up during our lifetimes? If we are none the worse for their flying away in carbonic acid and other things without ceremony, what good can we expect from having a fuss made about the body we leave behind us, which is put into the earth? However, you are wanting to know what becomes of the water and carbonic acid which have been made by the oxygen of the blood burning up the old materials of our frame. The dark blood of the veins absorbs this carbonic acid and water, as the blood of the arteries does oxygen,—only, they say, it does so by means of a salt in it, called phosphate of soda. Then the dark blood goes back to the lungs, and in them it parts with its carbonic acid and water, which escapes as breath. As fast as we breathe out, carbonic acid and water leave the blood; as fast as we breathe in, oxygen enters it. The oxygen is sent out in the arteries to make the rubbish of the body into gas and vapour, so that the veins may bring it back and get rid of it. The burning of rubbish by oxygen throughout our frames is the fire by which our animal heat is kept up. At least this is what most philosophers think; though doctors differ a little on this point, as on most others, I hear. Professor Liebig says, that our carbon is mostly prepared for burning by being first extracted from the blood sent to it—(which contains much of the rubbish of the system dissolved)—in the form of bile, and is then re-absorbed into the blood, and burnt. He reckons that a grown-up man consumes about fourteen ounces of carbon a day. Fourteen ounces of charcoal a day, or eight pounds two