"Put your hand on the tumbler, Felix," said Johnny.
Felix did so, but drew it back quickly. "It burns," said he.
"Yes," said Johnny: "chemical union causes heat, and there are two substances uniting here. You know the uniting of carbon or hydrogen with oxygen produces heat, and it's so with many other substances."
"It's going to run over!" said Sue.
Johnny slipped a saucer under the tumbler; and the black mass overflowed, half filling the saucer also.
"Now, you see," continued Johnny, "the particles of matter have changed very much; for one thing, it is plain enough that they are farther apart; the acid and the sirup would not have half filled the tumbler with their particles as near together as they were to begin with; but now they fill the tumbler and part of the saucer. Who says that there isn't charcoal for you? Just think, Felix! if you had eaten that sirup, you would have eaten so much charcoal: it would probably be more than you could burn up in your lungs to-day or to-morrow, with all the rest of the articles having carbon in them that you have eaten, and so you would have laid it up in extra fat on your body to use some other time, unless you keep on taking in more fuel than you need all the time; and, in that case, it would stay as stored fuel in the shape of fat, I suppose, unless the blood managed to carry off some of it to the lungs to be burned as waste matter. I don't exactly know about that: I haven't got very far in physiology yet."
"It's stopped smoking now," said Felix, taking up some of the black mass in his fingers. "I suppose it isn't good to eat with that poison acid in it."
"And it don't look very appetizing, either," replied Johnny. "But a person who had the right kind of apparatus, and knew how, could get all the sugar I put in there back again, so that it would be just as good to eat as it was before. I suppose that smoke was a gas escaping. I haven't studied into this experiment as I ought; but I shouldn't wonder if the oxygen in the water united with the acid, and that set the hydrogen in the water free, so that the 'smoke' was hydrogen gas. But I am not certain. I'll find out exactly how it is when I get back where my books are. Or, like enough, Pierre will tell us all about it."
"Well! This does look amazingly like charcoal," said Felix, "only it is sort of sticky. I guess we had better put it away till it dries."
"I don't believe it will dry," replied Johnny; "because that acid has such an affinity for water that it will collect moisture. It will stay just about as it is now; and, after you have looked at it enough, I had better throw it in the fire, where it will be out of the way: mother don't like to have any thing with poison in it about."