The form of a soda-water bottle is shown in fig. 2; it is made of very thick glass, that it may resist the outward pressure of the carbonic acid, and so formed that it cannot stand on its bottom, and when laid on its side the bubble of air shall rise up to the middle of the bottle and not to the cork, or else it would escape through the cork before long, however nicely it may be fitted. Illustration: FIG. 3. (‡ DISPENSING BOTTLE.) Fig. 3 is a convenient vessel for holding about a quart of soda-water or any other effervescing drink, all of which is not at once required. A tube passes from the top to nearly the bottom of the vessel, and when this is filled with aerated water, the expansive power of the carbonic acid forces the water up this tube and out of the spout when the handle is depressed and the tap opened, and when sufficient is obtained, the tap can be immediately closed. A very convenient apparatus called a “Gasogene” has lately been constructed. It consists of a double vessel, into the upper part of which a solution of any kind--wine and water, or even plain water--is put, to be saturated with carbonic acid or “aerated,” and into the lower one some carbonate of soda and tartaric acid. A tube leads from this lower to the top of the upper vessel, which screws on and off. By shaking the apparatus when thus charged and screwed together, some of the liquid descends through the tube into the lower vessel and moistens the soda and acid, which therefore act on each other, and cause carbonic acid to be disengaged; this, rising up through the tube (which is perforated with small holes at the upper part), disperses itself through the liquid in small bubbles, and causes sufficient pressure to enable the liquid to absorb it, which therefore effervesces when drawn off by the tap and this pressure removed. COAL-TAR NAPTHA. This is distilled from the coal-tar produced at the gas-house, the residuum being pitch, and it has a very offensive smell. It is in demand as a solvent for India-rubber, and also for use in lamps so constructed as to require no wick, for naptha is very volatile, and the vapour is burnt as it rises. WOOD NAPTHA, OR PYROXYLIC SPIRIT. This is often called wood spirit, and is procured from the tar resulting from the distillation of wood for wood vinegar or pyroligneous acid. It is colorless, without the disagreeable odour of coal-tar naptha, and very inflammable, burning without smoke, very much in the manner of spirits of wine. It is used in varnish-making, and also for burning in lamps where heat and not light is required. PRODUCTS OF SKILLED LABOUR. POTTERY. Illustration: (‡ POTTERY WORKERS.) Illustration: STAMPERS. Illustration: FLINT MILL.