800 



HONES AND HONE SLATES 



animal. Tho lists of imports below will show to what an extent a trado in the skins of 

 animals is carried on with this country. Wo receive hides largely from Russia and tho 

 north of Europe. From America there are also largo quantities brought to this country. 

 Tho following Table shows the number of hides which were imported in 1871 and 

 1872: 



HIGHGATE RESIN. A fossil copal occurring in the London clay of Highgato, 

 near London. 



HIPPOCASTANUM. Tho common horse-chestnut (Msculus Hippocastanum) t 

 The seeds contain much starchy matter, and have of late years been used on tho Con- 

 tinent for the preparation of starch. When roasted they are said to form a fair sub- 

 stitute for coffee. In Switzerland they are used as food for sheep. It is said that 

 the young leaves of the horse-chestnut have been used instead of hops. The 

 American Horse-chestnut or Buck-eye (another species of jEsculus) is reputed to be 

 poisonous. 



HIPPOPOTAMUS TEETH. See IVOHY. 



HISINGERITE. A hydrous silicate of peroxide of iron, magnesia, &c. ; from 

 Sweden. 



HISIiOPITE. A green calc-spar coloured with glauconite ; from India. 



HOG-GUM. The hog-gum of Jamaica, which is used locally as a medicine, is tho 

 produce of Rkus metopium. 



HOG-WITT. The edible fruit of Gary a porcina. 



HOG'S IiARX>, or Axungi ; the latter name derived from the use to which it was 

 put by the ancients, i.e. to grease the axle of a wheel. It is obtained from tho hog 

 (Sus scrofa) and other members of the hog tribe. Hog's lard is largely used in 

 the manufacture of ointments, pomatum, &c. Its proximate analysis gives, according 

 to Braconnot : stearine and margarine, 38 ; elaine, 62. Tho steariuo is separated 

 and used in the manufacture of candles, and the elaine sold under tho name of Lard 

 Oil. 



HOLING. The act of cutting away the under part of a coal-seam, so as to bring 

 down the overlying mass of coral. See MINING. 



HOLLAND. A linen fabric, which is sold when unbleached as brown holland, 

 and which is used when bleached for liner purposes. See LINEN. 



HOLLANDS. A grain spirit manufactured in Holland. 



HOLLY. (Le Houx, Fr. ; Stcchpalmc, Ger.) The Ilex aquifolium of Linnaeus, 

 a British plant. Its leaves yield a yellow colouring matter similar to that obtained 

 from buckwheat. Tho wood is as white as ivory, very hard and fine grained, and 

 susceptible of a high polish ; it is employed for many purposes. 



HOMBERG'S PHOSPHORUS. Sulphide of calcium, which after exposure to 

 sunlight appears luminous in the dark. 



HOMOGENEOUS. A uniformity of structure as applied to metals. Steel is said 

 to be homogeneous when the particles constituting the mass are of tho same size and 

 structure throughout. 



HOMOLOGOUS. A term used in organic chemistry to denote that substances 

 differ by the constant increment C 2 H 2 (CH 2 ). Thus, in the great series of acids com- 

 mencing with the formic and extending up to tho fatty acids, each homdoguc contains 

 C 2 H 2 more than the one before, and C 2 H 2 less than tho one following, thus : 



Formic acid 

 Acetic acid 

 Propionic acid . 

 Butyric acid 



HONDURAS M AHOGANY 

 HONES AND HONE SLATES. Th^<- aro slaty stones which aro usc-1 in 

 straight pieces for sharpening tools after they havo been ground on revolving grind- 

 stones. The more important varieties are the following: 

 Tho Norway Ragstone which is tho coarsest variety of the hone slates, is imported 



C 2 H 2 4 (CH'O 2 ) 

 CH 4 4 (C'H'O 2 ) 



C 6 H fl O' (c'H'o 2 ) 



C 8 H 8 (cH"0 2 ) &c. C.G.W. 



See MAHOGANY. 



