GAL 



GAM 



with a prickly surface, are formed on 

 the Q. cerris, dec. 



Gall-nuts contain tannic acid, yel- 

 low colouring matter, and gallic acid. 

 The decoction produces a variety of 

 coloured precipitates, with reagents ; 

 ■with solution of tin, a yellow ; alum, 

 a yellow gray ; acetate of copper, a 

 chocolate ; red sulphate of iron, a 

 blue black. They are used in making 

 ink and dyeing. See Tanmn. 



GALLINACEOUS. Birds resem- 

 bling the domestic cock ; as turkeys, 

 pheasants, pigeons. i 



GALLON. The imperial measure 

 contains 277-274 inches, or 10 pounds 

 of distilled water at 62° Fahrenheit. 

 It is equal to four quarts, or eight 

 pints. The old wine gallon contained 

 231 cubic inches ; the beer gallon, 282 

 cubic inches. Each of these stand- , 

 ards is used in diflerent states. The 

 half peck is a gallon in dry measure. 



GALLOWAY. A pony of 13 to 14 

 hands. Originally, a small breed of 

 horses. A variety of Scotch cattle. 



GALLOWS OF A PLOUGH. A 

 part of the plough head. i 



GALLS. In farriery, wounds pro- i 

 duced by the friction of harness. The 

 little tumours formed under saddles 

 are called warbles. Washing the 

 galled places with a solution of sugar 

 of lead, or keeping them clean with a 

 plaster of common ointment, or dress- 

 ing with Turner's cerate, and allow- 

 ing no farther pressure on the part 

 until it is healed, are the proper rem- 

 edies. Wtr.d- galls are little tumours 

 about the heels of horses over-driven. 



GALVANISM. That form of elec- 

 tricity produced by the chemical ac- 

 tion of one body on another. A sim- 

 ple galvanic circle or arrangement 

 consists of a metal subject to the ac- 

 tion of the fluid, and a second not in- 

 fluenced thereby, an exciting fluid, 

 with wires, called poles, proceedmg 

 from each metal. The most com- 

 mon materials are zinc, copper, and 

 sulphuric acid diluted with twelve 

 parts water. The acid acts on the 

 zinc only, and the electricity so pro- 

 duced is conveyed along the wires or 

 poles. No galvanism passes until the 

 poles are brought in contact ; any flu- 

 311 



id or body between them, which is an 

 im[ierfect conductor, is heated or de- 

 composed by the current. A galvan- 

 ic pile consists of a series of the two 

 metals so arranged that the coppers 

 and zincs touch in pairs : two poles 

 at the extremities discharge the elec- 

 tricity produced by the whole appa- 

 ratus. Other metals and fluids are 

 used, as well as peculiar arrange- 

 ments contrived for the production 

 of a continuous current. For the ap- 

 plication of galvanism to agriculture, 

 see Electricity. There are two con- 

 ditions of the galvanic fluid referred 

 to by chemists, i. e., quantily and ten- 

 sion. Quantity is produced by using 

 very large surfaces of metal and 

 strong exciting fluids ; tension by 

 employing numerous pairs. 



GALVANOMETER. " An instru- 

 ment for ascertaining the presence 

 of a current of electricity, especially 

 galvanic or voltaic electricity, by the 

 deviation which it occasions in the 

 magnetic needle. The , 

 simplest form of gal- \ 

 vanometer is a mag- 

 netic needle poised 

 upon a point, and sur- 

 rounded by one or 

 more coils of copper wire, covered 

 with silk, the ends, a and A, being ei- 

 ther left free, or termmating in two 

 small copper cups containing mercu- 

 ry, for the convenience of communi- 

 cation with the source of electricity. 

 When this needle is placed parallel 

 to the coil, and in the magnetic me- 

 ridian (as represented in the margin), 

 it immediately deviates when the 

 electric current passes through the 

 coil ; and the deviation is either to 

 the east or the west, according to th.e 

 direction of the current." — (Bravde.) 



GAM A GRASS. Tripsacum dac- 

 tyloides. A coarse, perennial, indi- 

 genous southern grass, growing to 

 four or five feet. It is very produc- 

 tive, and may be propagated by seeds 

 or roots. The cultivation is scarce- 

 ly thought advantageous. 



GAMBOGE. The dry juice of the 

 Stalagmites Cambngioides and other 

 East Indian trees. This colour is a 

 gum resin ; it is poisonous, a drastic 



