Page:First course in biology (IA firstcourseinbio00bailrich).pdf/28

 to be understood, the following questions, together with any others which suggest themselves, may be asked: What is the reason that draughts are opened in stoves? Why is the bottom of a "burner" on a lamp always full of holes?

II. Carbon

Let us now observe the blackened end of a burned match or splinter. This black substance is usually known by the name of charcoal. If handled, it will blacken the fingers. Try this. The same substance is found on the bottoms of kettles which have been used over a wood fire, but it is there a fine powder.

Let us see what was burning when the candle was lighted, besides the oxygen in the air. Relight the candle and hold the porcelain or glass about an inch above the bright part of the flame. What happens to it there? Next, lower it directly into the flame (C). What is the black stuff that gets on the glass? Look closely and see whether it is not deposited here also as a fine powder. Will this deposit from the candle blacken the fingers?

C.—

Instead of using the name charcoal for this black substance, let us call it carbon, the better name, because there are several kinds of carbon, and charcoal is only that kind which is rather light and easily blackens the hands.

The carbon from the candle flame came mostly from the wax or tallow; only a very small part came from the wick. It cannot be seen in the tallow, neither can it be seen in