267 



GALLSTONE. 



GALLON. 



258 



used, but vinegar must be avoided. The dread of similar casualties 

 from the employment of the spurious instead of the genuine Angos- 

 tura bark, has prevented the use of the latter to that extent which 

 it merits. In the treatment of the bilious diarrhoea, frequent in 

 damp autumns in this country, after proper evacuants, it is of the 

 most decided utility. In common English cholera likewise, and 



slighter cases of Asiatic cholera, it is the most beneficial agent which 

 can be resorted to. It is best given in the form of infusion, and may 

 either be administered alone, or with the addition of dilute nitric acid 

 and tincture of opium, which last may be discontinued after a few 

 doses. (Abercrombie, ' On Diseases of the Stomach,' &c.) 

 Re-agents produce the following effects on a cold infusion, of each : 



Colour of Infusion of Genuine, Orange Yellow. Colour of Infusion of Spurious, Light Yellow. 



GALLSTONE. [CHOLESTERIN.J 



GALL-STONES. [CALCULUS.] 



GALLAMIC ACID. [TAXNIC ACID.] 



GALLATES. [TiSNic ACID.] 



GALLEON (yaUiion in French, yalcn in Spanish) was the name 

 given to very large ships, with three or four decks, of which many 

 were employed in the Spanish Armada in 15SS. Subsequently the 

 name became restricted to the large vessels which the court of 

 Spain used to send at fixed periods to the coasts of Mexico and 

 Peru, to receive on board the gold and silver bullion extracted from 

 the mines, and bring it to Spain. Commodore Anson intercepted, 

 and captured after a short engagement, one of these galleons on its 

 way from Acapulco to Manilla. 



GALLERY of Mine is the passage leading from the shaft or entrance 

 of the mine to the place where the powder is deposited. [MixE, 

 MILITARY.] 



GALLERYTHRONIC ACID. [TANXIC ACID.] 



GALLEY (galHre in French, galera in Italian and Spanish), a large- 

 sized vessel propelled by oars and sails, which was much in use in the 

 Mediterranean until the end of the ISth century. It carried two 

 marts with lateen Bails, was long and narrow, and drew but little 

 water; it was therefore calculated for coast navigation, and for 

 making the shore in shallow water ; and by means of its oars it had a 

 great advantage, in the dead calms so frequent in the Mediterranean, 

 over sailing vessels, an advantage in which it has been effectually 

 superseded by the introduction of the steam-boat. Even long before 

 that invention the use of galleys as a naval force had been given up by 

 France, their construction rendering them unfit for long navigation, 

 and for encountering the waves of the ocean. The Knights of Malta, 

 Naples, the Pope, and other Italian states, were the last to continue 

 the use of galleys for the purpose of coping with the Barbary 

 privateers, whose vessels, although of a similar description, were 

 generally smaller and unable to resist the large and well-disciplined 

 galleys of the Christian powers. The largest galleys were ICO feet long 

 and about 32 wide, with 52 oars. The rowers, who were generally 

 convicts or Turkish prisoners, with chains to their feet, sat on benches 

 on the deck. The ship carried a 24-pounder and two 8-pounders. 

 (See a description and plate of a large-sized galley in the ' Dictionnaire 

 de Marine,' article (ialerf. in the ' Encyclopedic Methodique.') 



The galleys appear to have been an imitation of the ancient triremes, 



and they retained the ancient names for several parts of the rigging, 



such as " antenna," &c. The felucca is a kind of small galley. 



[FELUCCA.] The Venetians had a sort of large galley, with a very 



; <>op, called " Galeazza." 



(i-YLLIARD (Gagliarda, Ital.), a lively dance in three-crotchet time, 

 which had its origin in Koine, but has fallen into disuse. 



GALLIC ACID. (3HO,C,,H !1 0, + 2Aq.) The well-known astringent 

 property of various parts of plants is due to the presence of tannic or 

 gallic acids. Gallic acid occurs in far less abundance than tannic acid. 

 It may be extracted directly, by precipitating tannic acid from an 

 aqueous infusion of a bark, root, &c., by means of solution of gelatine, 

 and then evaporating the filtered liquid, which contains the gallic acid, 

 to dryness. The residue, digested in alcohol, treated with animal 

 charcoal and the solution allowed to evaporate spontaneously, yields 

 the gallic acid in a crystalline state. 



Gallic acid is, however, usually prepared by a kind of fermentation 

 from the tannic acid in nut-galls. [GALLS, in NAT. HIST. Div.] 

 Powdered galk, well moistened with water, are exposed in a warm 

 place to the action of the air for two or three months. Mould rapidly 

 forms on the surface of the mass, and must be occasionally removed ; 

 oxygen is absorbed and carbonic acid evolved. On subsequently 

 boiling the whole in a considerable quantity of water, gallic acid is 

 .ed out, and is deposited in crystals on the cooling of the 

 liquor. 



W I quito pure, by recrystalliaation from alcohol, and 



ABTS AA-U SCI DIV. VOL. IV. 



the usual treatment with animal charcoal, gallic acid is obtained 

 in long, silky, nearly colourless needles or prisms of astringent taste, 

 but no odour. They are soluble in one hundred times their weight 

 of cold water, but in three parts of boiling water. Alcohol dissolves 

 them readily, ether only sparingly. A heat of from 410 to 420 

 Fahr. causes the decomposition of gallic acid into pyrogattic acid 

 which sublimes in brilliant white crystals, and carbonic acid, which 

 is evolved as gas. The sudden application of too high a temperature 

 (above 480) to gallic acid causes the evolution of water as well as 

 carbonic acid and metagallic acid or gallulmic acid remains. Ebul- 

 lition with strong solution of potash converts gallic acid into tan- 

 nomelanic acid. Gently heating with sulphuric acid converts it 

 into rufyallic acid, while nitric acid rapidly oxidises gallic acid to 

 oxalic acid. 



Gallates are formed by the union of gallic acid with bases. In this 

 way three classes of salts result : 



Monometallic salts 

 Bimetallic salts . 

 Trimctullic salts 



MO, mo, C lt H 3 O, 

 2MO, HO, C J4 U 3 0, 

 3MO, C lt H,0, 



In the solid state the gallates are tolerably stable, in solution they 

 rapidly absorb oxygen if exposed to the air and are decomposed. The 

 characteristic reaction for the detection of gallic acid is the production 

 of a deep bluish-black solution on the addition of a mixture of proto- 

 and per-salts of iron. 



GALLIOT, a strong-built flat-bottomed vessel of a peculiar con- 

 struction, used as a bomb-ship to fire against forts or batteries on the 

 coast. The largest are of the burden of 400 or 500 tons, and above 

 100 feet in length. See account and plate of the same in the ' Diction- 

 naire de Marine,' in the ' Encyclopedic Me"thodique,' art. " Galiotte." 

 Galliot is also a kind of small galley or large felucca, used chiefly in 

 the Mediterranean, especially by the Barbary corsairs. [GALLEY.] 

 The Dutch, Swedes, and other northern nations have a sort of 

 merchant-ship which they call Galliot, heavy and clumsily built, but 

 strong of timber, rounded both fore and aft, and of the burden of 

 from 200 to 300 tons. 



GALLITANNIC ACID. [TANXIC ACID.] 



GALLON, an old English measure of capacity. The Latin of the 

 middle ages is gato, galuna, jalo, lagena, &c. Dr. Bernard thinks the 

 latter is the original. Ducange cites an old assize of David of Scotland, 

 in which it is said the lagena should contain 12 Ibs. of water, namely, 

 4 of sea water, 4 of still water, and 4 of running water. But that 

 various gallons were used is evident from statutes of Henry III. and 

 later kings, in which it is enacted that ale, wine, and corn shall be 

 measured by the same gallon, containing eight troy pounds of dry 

 wheat from the middle of the ear. These statutes produced no effect, 

 and distinct gallons for wine, ale, and beer, and corn and dry goods, 

 continued in use until the Act of 5 Geo. IV., c. 74, which came into 

 operation May 1, 1825. 



By statutes of 1689 and 1697, the wine gallon was declared to con- 

 tain 231 cubic inches. But in 1688, by <m experiment, at which 

 Flamsteed, Halley, and others (among whom was Ward, author of the 

 'Young Mathematicians' Guide," who relates the circumstance) were 

 present, it was very distinctly proved that the sealed gallon at Guildhall 

 (which was the usual standard) contained only 224 cubic inches. 

 " However," says Ward, " for several reasons it was at that time thought 

 convenient to continue the former supposed content of 231 cubic 

 inches." The fact was, that the Guildhall gallon was an incorrect 

 copy of the old Exchequer standard, placed in a more accessible 

 locality. Previously to this, Dr. Bernard had stated his full con- 

 viction, from the measurements of predecessors whom he cites, that 

 the said gallon contained 223'549 cubic inches ; the agreement of these 

 two experiments leaves no doubt as to their accuracy. By the Act of 

 the 6th of Quueu Anne, the wine gallon of 231 inches was m.-ido the 

 standard ; and a gallon was accordingly constructed for the Exchequer, 



8 



