290 BARLEY 



barytes or heavy spar. Professor Dana has proposed that a distinction should be 

 established between the names of minerals and those of rocks, by terminating the 

 former in -tie and the latter in -yte. Hence the change of spelling from baryte to 

 barite. 



BARIUM. (From ftapvs, heavy.) The metallic basis of the earth baryta was 

 obtained by Davy, in 1808, by the voltaic decomposition of the moistened carbonate 

 of baryta in contact with mercury. It may likewise bo procured by passing potassium 

 in vapour over baryta heated to redness in an iron tube, and afterwards withdrawing 

 the reduced barium which the residuum contains, by means of mercury. The latter 

 metal is separated by distillation in a glass retort, care being taken not to raise the 

 temperature to redness, for the barium then decomposes glass. Mr. Crookes has 

 prepared metallic barium by adding a saturated solution of chloride of barium to his 

 sodium-amalgam, and heating it to about 200 F. The sodium is thus replaced by 

 barium, and this barium-amalgam, when purified, is heated \inder naphtha, and the 

 mercury thus distilled off, leaving metallic barium. 



Barium is a white metal, like silver, fusible under a red heat, and denser than 

 oil of vitriol, in which it sinks. Graham. 



BARIUM, OXIDES OF. There are two oxides of barium, a protoxide EaO 

 (baryta) and a peroxide BaO 2 . Tho protoxide will bo described under BABYTA. 

 The peroxide may bo obtained by passing oxygen over caustic baryta heated to dull 

 redness ; the oxygon thus absorbed may be expelled at a higher temperature, and the 

 peroxide thus reduced to the state of protoxide. Availing himself of these reactions, 

 Boussingault has proposed to prepare oxygen gas on a largo scale by first forming 

 peroxide of barium by the passage of atmospheric air over baryta at a low red heat, 

 and then decomposing this peroxide by ignition. Tho oxygon would thus be really 

 derived from the air, and the barium-oxide would merely act as a medium for its 

 alternate absorption and evolution, and might therefore bo used over and over again 

 indefinitely. Though economy seems to recommend this process, there are practical 

 difficulties which have hitherto interfered with its working. See BARYTA. 



BARIUM, SALTS OF : 



BROMIDE OF BARIUM. Prepared by saturating baryta water with hydrobromic 

 acid. 



CHLORIDE OF BARIUM. Made from the native sulphate (heavy spar), by igniting 

 it in a crucible with pounded coal, and then dissolving this sulphide in hydrochloric 

 acid, or by fusing the native sulphate with chloride of calcium. Tho commercial 

 chloride frequently contains small quantities of the chlorides of strontium and calcium. 

 Chloride of barium is especially used for the detection and estimation of sulphuric 

 acid. 



FLUORIDE OF BARIUM. Prepared by neutralising baryta-water by hydrofluoric 

 acid. 



IODIDE OF BARIUM is formed when hydriodic acid is passed over baryta at a rod 

 heat. 



BARK. Tho outer rind of plants. Many varieties of barks are known to com- 

 merce, but the term is especially used to express either Peruvian or Jesuits' bark, n, 

 pharmaceutical remedy, or Oak bark, which is very extensively used by tanners and 

 dyers. The varieties known in commerce are : 



CORK BARK. (Fr. Liicje ; Kork, Gor.). OAK BARK. (Tan brut, Fr. ; Eichenrlnde, 

 Ger.). PERUVIAN BARK. ( Quinquina, Fr. ; Chinarinde, Ger.). QUERCITRON BARK. 

 WATTLE BARK. See these respectively. 



BARX BREAD, A kind of bread prepared in many parts of Norway by the 

 poorer peasants from the inner bark of the Pinus sylvestris. See PINUS. 



BARIiEY. (Orgc, Fr. ; Gerste, Ger.) Hordeum, Linn. This term is supposed 

 to bo derived from hordus, heavy, because the bread made from it is very heavy. 

 Barley belongs to the class Endogcns, or Monocotyledons ; Glumcl Alliance, of Lindley : 

 natural order, Graminacea. 



There are four species of barley cultivated in this country : 



1. Hordeum Jiexastichon. Six-rowed barley, or Winter barley. 



2. Hordeum vulyare. The Scotch bero or bigg ; the four-rowed barley. 



3. Hordeum seocriton. Putney, fan, sprat, or battledore barley. 



4. Hordeum distichon. Two-rowed long-eared barley, or Summer barley. 

 Barley and oats are the cereals whose cultivation extends farthest north in Europe. 

 The specific gravity of English barley varies from T25 to 1'33 ; of bigg from 1-227 



to 1 '265 ; the weight of the husk of barley is ^, that of bigg . Specific gravity of 

 barley is T235, by Dr. Uro's trials. 1,000 parts of barley-flour contain, according to 

 Einhof, 720 of starch, 56 sugar, 50 mucilage, 36'6 gluten, 12-3 vegetable albumen, 

 100 water, 2'5 phosphate of lime, and 68 fibrous or ligneous matter. 

 From the examination instituted by the Royal Agricultural Society of England, and 



