[Footnote 17: Page 152. _Marble_ is a compound of carbonic acid and lime.
The muriatic acid being the stronger of the two, takes the place of the carbonic acid, which escapes as a gas, the residue forming muriate of lime or chloride of calcium.]
[Footnote 18: Page 186. _Lead pyrophorus_ is made by heating dry tartrate of lead in a gla.s.s tube (closed at one end, and drawn out to a fine point at the other) until no more vapours are evolved. The open end of the tube is then to be sealed before the blowpipe. When the tube is broken and the contents shaken out into the air, they burn with a red flash.]
[Footnote 19: Page 216. _Water-gas_ is formed by pa.s.sing vapour of water over red-hot charcoal or c.o.ke. It is a mixture of hydrogen and carbonic oxide; each of which is an inflammable gas.]