634 GERMAN SILVER 



and mixing with it oxide of iron, the green shade may be varied, and the periodot or 

 the deep-tinted emerald may bo imitated. 



The manufacture of artificial gems has acquired an extreme development ; immense 

 factories are established at Septmoncal in the Jura, furnishing employment to more 

 than 100 work people, who produce fabulous quantities. 



Many ingenious persons in Paris vie with each other -in bringing to perfection the 

 most perfect processes, and produce truly surprising results. M. Savary especially, 

 in his magnificent collections, and his perfect imitation of celebrated diamonds, has 

 arrived at a degree of excellence which, apparently, can scarcely be surpassed. 



We have alluded only to those imitations of gems in glass of which a largo portion 

 of the cheap jewellery is formed. Some very successful attempts have been made to 

 manufacture true gems by an artificial process. M. Ebelmen has done much in this 

 direction, and M. Henri Sainte-Claire Deville and M. Henri Caron communicated to 

 the Academy of Sciences of Paris, in April 1858, a process which they had discovered 

 for the production of a number of the gems which belong to the corundrum class, as 

 the ruby, sapphire, &c. Essentially, the process consisted in exposing the fluoride 

 of aluminium, mixed with a little charcoal and boracic acid, in a black-lead crucible, 

 protected from the action of the air, to a white heat for about an hour. For details 

 of the process, see Comptes Rendus, and Annales de Chimie. 



GENAPPE. A worsted yarn used in the manufacture of fringes, braids, &c. 

 From its smoothness it combines very readily with silk. 



GENEVA. A grain-spirit flavoured with juniper-berries, manufactured exten- 

 sively in Holland ; hence it is frequently called HOLLANDS. 



GENISTA. A genus of papilionaceous plants. G. tinctoria is the Dyer's Broom, 

 which yields a yellow die, or, when mixed with woad, a green colour. A sprig of 

 genista was the badge of Henry II.'s father, whence the family name Plantagenet 

 (flanta genista). 



GENTIAN. Gentiana lutea. The common or yellow gentian, which is said to 

 owe its name to Gentius, king of Illyria, who introduced it as a medicine about 170 

 years before Christ. 



The roots of the gentian are collected and dried by the peasants of Switzerland, 

 the Tyrol, and in the Auvergne. 



The bitter of the gentian is agreeable and aromatic ; it is much used in medicine, 

 and has on some occasions been employed instead of hops in beer. 



GEOCRONITE. A native sulphantimonide of lead, from the silver mines of Sala, 

 in Sweden. It appears to resemble KILBRICKENITE. 



GEODE. A rounded nodule of stone, containing a cavity usually lined with 

 crystals. Geodes frequently consist of agate, chalcedony, &c. See AGATE. 



GEOGNOSY (777, the earth, and yvwois, knowledge), means the science of the 

 substances which compose the earth's crust. It originated with the German mine- 

 ralogists, 



GEOLOGY (77), the earth, and \6yos, a discourse). The science which treats of the 

 structure of the earth, and of the causes which have produced its present physical 

 features. 



GERANIUM, OIXi OF. A name sometimes applied to the oil of ginger-grass, 

 which is prepared in the East from certain species of Andropogon. This has of course, 

 no relation whatever either to our wild geraniums (crane's bills) or to our garden 

 geraniums (Pelargoniums). 



GERHARDT'S ANHYDROUS ACETIC ACID. See ACETIC ACID, and 

 Watts' s 'Dictionary of Chemistry.' 



GERMAN BI.ACK. See FRANKFORT BLACK. 



GERMAN SILVER. M. Gersdorf, of Vienna, states that the proportion of 

 Ithe metals in this alloy should vary according to the uses for which it is destined. 

 jWhen intended as a substitute for silver, it should bo composed of 25 parts of 

 : nickel, 25 of zinc, and 50 of copper. An alloy bettor adapted for rolling consists 

 of 25 of nickel, 20 of zinc, and 60 of copper. Castings, such as candlesticks, bells, 

 &c., may be made of an alloy, consisting of 20 of nickol, 20 of zinc, and 60 of copper ; 

 to which 3 of lead are added. The addition of 2 or 2 of iron (in the shape, of 

 tin plato ?) renders the alloys much whiter, but, at the same time, harder and more 

 brittle. 



Keferstein has given the following analysis of the genuine German silver, as made 

 from the original ore found in Hildburghausen, near Suhl, in Henneberg : 



Copper 40'4 



Nickel 31-6 



Zinc 2;V1 



Iron 2-0 



JOO-0 



