B A L 



BAR 



end, instead of in the middle ; and also, 

 in having the weights suspended hy 

 hooks instead of being placed in a dish. 

 Here the fulcrum is between the power 

 and the weight. This is the principle 

 also of the Chinese balance. 



2. Danish Balance. This kind of lever 

 consists of a bar of wood or iron, having 

 a leaden weight at one extremity, and 

 the goods to be weighed fixed in a hook 

 at the other. The bar is suspended by 

 a loop, which is moved backward and 

 forward until the equilibrium is obtained. 

 The weight of the goods and the leaden 

 weight are then to each other recipro- 

 cally as their respective distances from 

 the loop. 



BALANCE ELECTROMETER. An 

 instrument constructed on the applica- 

 tion of the common balance and weights, 

 for the purpose of estimating the mutual 

 attraction of oppositely electrified sur- 

 faces. 



BALANCE OF TORSION. A deli- 

 cate electrometer, invented by Coulomb, 

 on the principle of establishing an equi- 

 librium between the force of electricity 

 and that of the torsion, or twisting, 

 of a fibre of the web of the silk-worm. 



BA'LANCERS. A term generally ap- 

 plied to the posterior pair of wings in 

 Dipterous insects, in wiiich they appear 

 in the condition of minute clavate ap- 

 penda!?es. 



BALANI'DA ( balantis, an acorn). 

 Acorn-barnacles ; an order of Cirrhopods, 

 named from the genus balanus, and cha- 

 racterized by their being enclosed in a 

 conical shell, adherent by its base to 

 foreign substances, and closed at its apex 

 by four valves. 



BA'LANOPHO'RE^. A small fa- 

 mily of leafless rhizanths, parasitical 

 upon roots, named from the genus bala- 

 nophora, and natives of the West Indies, 

 South America, &c. Their properties 

 are unknown. 



BA'LAS RUBY. A technical term 

 for the bright red varieties of the spinel, 

 a sub-species of ruby. 



BALAU'STA {/3a\av<TTiov, the flower 

 of the wild pomegranate). A term ap- 

 plied, in Botany, to the many-celled, 

 many-seeded, inferior, indehiscent fruit 

 of the pomegranate. 



BALDWIN'S PHOSPHORUS. The 

 ignited nitrate of lime. This salt de- 

 rives its name from its property of emit- 

 ting a beautiful white light in the dark, 

 when kept in a stoppered phial, and ex- 

 posed for some time to the rays of the sun. 

 47 



BALLI'STIC PENDULUM (/3d\\<a, 

 to throw). A heavy wooden pendulum, 

 for measixring the velocity of cannon and 

 musket balls, and for determining the 

 resistance of the air to rapid motions. 

 The mechanical problem to be solved is 

 this : — Given, the weight of the shot, the 

 place at which it strikes, the weight, 

 form, &c., of the pendulum, and the 

 number of vibrations produced upon it 

 by the shot ; required, the velocity of the 

 shot. 



BALLOON {ballon, French, a little 

 ball). A chemical instrument or re- 

 ceiver, of a spherical form, for condens- 

 ing vapours from retorts. The term 

 balloon signifies any spherical hollow 

 body, of whatever material composed, or 

 to whatever purpose applied : in its most 

 common use, it denotes a machine for 

 navigating the air. 



BA'LSAMS. Vegetable juices, either 

 liquid, or becoming spontaneously con- 

 crete, and consisting of ethereal or 

 essential oils with resin and benzoic acid. 

 The liquid balsams are copaiva, opo- 

 balsam, balsam of Peru, storax, and 

 Tolu ; the concrete are benzoin, dragon's 

 blood, and red or concrete storax. Those 

 compounds which have no benzoic acid 

 are miscalled balsams, being, in fact, true 

 turpentines. 



BALSAMA'CEtE. BalsamiflucB. An 

 order of Dicotyledonous plants, found ia 

 tropical India, and characterized by their 

 balsamic products. The fragrant resin 

 storax is yielded by several species of 

 Liquidambar, the only genus of the 

 order. 



BALSAMINA'CEiE. The Balsam 

 tribe of Dicotyledonous plants ; a small 

 order of plants, closely allied to the 

 GeraniacecE, and chiefly remarkable for 

 the elastic force with which the valves of 

 the fruit separate when ripe, and expel 

 the seeds. 



BANDA'NA. A mode of calico print- 

 ing practised in India, by which white or 

 brightly coloured spots are produced upon 

 a red or dark ground. 



BARBA'DOS TAR. Petroleum. A 

 species of bitumen, differing from naphtha 

 in its greater weight and impurity. 



BARDIGLIO'NE. A blue variety of 

 anhydrite, cut and polished for orna- 

 mental purposes. 



BARI'LLA. The commercial name of 

 the impure carbonate of soda extracted 

 from the ashes of the plants salsola and 

 salicornia, and imported from Spain or 

 the Levant. Kelp, or British barilla, is 



