As the result of experiments with charcoal, an English chemist avers that for the reduction of metallic oxyds, the charcoal of the heavier woods (as that of oak and the beech) is preferable; and that, for common fuel, sneh charcoal gives the greatest heat, nnd reqnires the most plentiful supply of air to keep it burning, while those of the lighter woods preserve a glowing heat with mnch less draft of air; and that for pnrposes where it is desirable to have a steady and a still fire, charcoal shonld be employed which has been made from wood previously divested of its bark, since it is the cortical p"rt which flies off in sparks during the combnstion, while tha coal of the wood itself seldom does.