Q. Why do not “Argand burners” smoke?
A. Because a current of air passes through the middle of the flame; and therefore the carbon of the interior is consumed, as well as that in the outer coating of the flame.
Q. Why does a lamp-glass diminish the smoke of a lamp?
A. Because it both concentrates and reflects the heat of the flame; in consequence of which, the heat is so greatly increased, that very little carbon escapes unconsumed.
CHAPTER VI.
ANIMAL HEAT.
Q. What is the cause of animal heat?
A. Animal heat is produced by the combustion of hydrogen and carbon in the capillary veins.