[Illustration: Fig. 150. A. A carriage with six fire annihilators, No. 5 size, fitted with moveable pipes. The body of the carriage forms a tank for forty gallons of water; the tank is filled at a bunghole in the platform; a patent tap is fitted to the rear of the carriage; a spigot is placed near the end upright of the rail; a hand-pump is placed in the box at rear of carriage; a leather bucket with foot-holds and three canvas buckets are hung on the carriage; a hammer for removing and driving on the cover of the fire annihilator, and a nut wrench for the No. 10 truck, are placed in the box. B. A fire annihilator, No. 10 size, with moveable pipe, on a spring truck, is attached to the carriage. The battery is fitted with shafts for one horse. A pole is also provided to fix across the shafts, so that the battery may be drawn by hand.] [Illustration: Fig. 151. A. Tank containing acid, communicating by a pipe with B, half filled with chalk and water. C C C C. Pipes conveying carbonic acid from the generator B, to the ceiling, where it is discharged from numerous holes on the fire beneath.] Monsieur Adolphe Girard has proposed that all houses should be provided with an apparatus for the generation of carbonic acid gas, placed [Page 161] outside the building, which is to be conveyed along the ceiling by means of pipes perforated with numerous holes, and to be put in operation directly a fire breaks out. This plan, however ingenious, could hardly supply the carbonic acid gas with sufficient rapidity, and it is to be feared would utterly fail in practice. (Fig. 151.) BORON. Symbol, B; combining proportion, 10.9. Discovered by Homberg, in 1702, in borax, which is a biborate of soda (NaO,2BO_{3}), and is used very extensively in the manufacture of glass; also for glazing stoneware and soldering metals; it is also a valuable flux in various crucible operations, whilst in testing minerals with the blowpipe it is invaluable. Borax is made either from tincal, a substance that occurs naturally in some parts of India, China, and Persia, or by the addition of carbonate of soda to boracic acid, a substance obtained from the volcanic districts of Tuscany, whence it is imported to this country, and used in the manufacture of borax.