O A 



34G 



r, A M 



low extractive matter, galls contain tan- 

 iiia or tannic acid, and gallic acid. Those 

 from Aleppo are the best. 



GAL'LON, a measure of capacity, both 

 for liquid and dry articles, containing 

 4 quarts or 8 pints. The imperial gallon 

 is the standard measure of capacity, and 

 should contain 10 Ibs. avoir, of distilled 

 water, weighed in air at 62" Pali., the 

 barometer being at 30 inches. It is there- 

 fore equal to 277.274 cubic inches. The 

 old English wine gallon contained 231 

 cubic inches, and the ale gallon 282 cubic 

 inches. The gallon of dry measure con- 

 tained 268.8 cubic inches. 



GALLO'ON, a narrow kind of lace used to 

 edge or border cloths : formerly made of 

 gold, silver, or silk. 



GALLOPA'DE. In the manage, a sort of 

 curvetting gallop. It is the name also of a 

 sprightly kind of dance. 



GAL'LOPEK. In artillery, a carriage which 

 bears a gun of a pound and a half ball. 



GAI/LOWS BITS (.of a ship), a frame of 

 timber, forming a support for the spare 

 topmasts, yards, and booms. 



GALI/STONE, a name common to all cal- 

 careous concretions found in the gall- 

 bladder. 



GA.I/I or GATJLT, a provincial name for a 

 etin marl, varying in colour from a light 

 erey to a dark blue : sometimes called the 

 Folkstone marl. It is a member of the 

 ^Ttraceous group of strata, and is rich in 

 fon&t 



^iLVAx'ic TROUGH, ) An apparatus em- 



njLrvAN'ic BATTERY, j ployed in accu- 

 mulating galvanism. It consists of a 

 number of pairs of metallic plates, usually 

 fitted into a trough made to contain the 

 exciting fluid. There are two wires sol- 



dered to the extreme plates, one of which 

 is copper and the other zinc, called the 

 poles of the battery. Sometimes several 

 single troughs are connected together, 

 when a very powerful apparatus is re- 

 quired. 



GAI/VANISED IRON, a fantastic name 

 lately given in France to iron tinned by 

 a peculiar patent process, whereby it is 

 rendered less liable to be acted upon by 

 moisture. 



GAL'VANISM, a modern and highly in- 

 teresting branch of science, thus named 

 after Prof. Galvani, of Bologna, who first 

 called attention to some of its pheno- 

 mna. Making some electrical experi- 

 ments, while near the machine were some 



frogs t'.i.it had been flayed, he observed 

 that the limbs became convulsed every 

 time a spark was drawn from the appara- 

 tus. He-ascribed these movements to an 

 electric fluid or power innate in the living 

 frame, or capable of being evolved by it, 

 and which he denominated animal elec- 

 tricity. The power of the electric eel fur- 

 nished plausible analogies. But Volta a d - 

 vanced some powerful arguments against 

 the hypothesis of Gfllvam, aud showed 

 that the muscular commotions, and many 

 other phenomena afterwards noticed, 

 were ascribed to arrangements not pre- 

 viously thought of by the scientific 

 world. He found that when two pieces 

 of different metals were placed in contact 

 with different parts of an animal, and 

 were brought into connexion by means 

 of a metallic arc, convulsions ensued every 

 time, and that this effect was strongest, 

 when the metals were silver and zinc. 

 This gave the idea of the pile battery, and 

 to which the epithets galvanic and voltaic 

 are indifferently applied : and indeed so 

 decided were the experiments and rea- 

 sonings of Volta, that the name of the 

 science itself was nearly being changed 

 from galvanism to voltaism. The name 

 current electricity is now sometimes used, 

 on the hypothesis that galvanism is elec- 

 tricity developed by chemical affinity ! 



GALVANOM'KTER, an apparatus contrived 

 to measure the force of a galvanic current. 

 It consists usually of a magnetic needle 

 freely supported upon a point, wituin the 



rectangle of a copper wire, placed in con- 

 nexion with the poles of a galvanic cir- 

 cuit by the mercury cups at the extremi- 

 ties: the needle is deflected from the 

 magnetic meridian, and forms an angle 

 with it, proportioned to the strength of 

 the current. Dr Kitchie's torsion gal- 

 vanometer is much more delicate than 

 this, but the principle is the same. 



GAMBO'OE, a concrete vegetable juice, 

 or gum-resin , whicR exudes from several 

 trees, but especially the Garcinia Cambo- 

 giodes, a forest tree which grows upon 

 the banks of the river Kamboja in Siam. 

 It is used extensively as a yellow pigment. 

 and also in medicine in doses from 2 to 6 

 grains. 



GAM'ELION, the eighth month of the 

 Athenian year, containing 29 days, and 

 answering to the latter part of our Ja- 

 nuary and beginning of February. 



