310 i:\AP01UTION 



the West Indies, &c. It is said that at the Capo the cultivation of this tree lias com- 

 pletely changed the unhealthy character of parts of the colony. The bark and leaves 

 of this species are reputed to possess febrifugal properties. 



EUCHROITE. A hydrous arsenato of copper, occurring in green crystals, of tho 

 rhombic system, at Libethon in Hungary. 



EUCIiASE. A silicate of alumina and beryllia, allied to the emerald. It crystal- 

 lises usually in small colourless crystals belonging to tho oblique system, and 

 exhibiting highly perfect cleavage. The stone is sufficiently hard to bo cut and 

 polished, but is of no value to the jeweller in consequence of its extreme brittlenoss ; 

 indeed, this fragility suggested the name to Haiiy (v, eu, perfect ; K\dw t klao, to 

 cleave). The euclase is found in Brazil and in the Ural Mountains. 



EUDIOMETER is the name of any apparatus subservient to the chemical exami- 

 nation of the atmospheric air. It moans a measure of purity, but it is employed merely 

 to determine tho proportion of oxygen which it may contain. The explosive eudio- 

 meter in which about two measures of hydrogen are introduced into a graduated glass 

 tube containing five measures of atmospheric air, and an electric spark is passed 

 across tho mixture is tho best of all eudiometers ; and of these, the siphon form 

 proposed by Dr. Ure, in a paper published by tho Royal Society of Edinburgh, in 

 1819, is tho most convenient. 



EUGENIA. A genus of plants of the order Myrtacea, called after Prince Eugene 

 of Savoy. Eur/rnia Pimento, is tho Allspice Tree. This tree is cultivated largely 

 in tho West Indies in regular walks, known as 'Pimento walks.' The Pimento is the 

 dried unripe berries of the Pimenta. When the fruit has attained its full size, but is 

 yet green, it is gathered and sun-dried. It is afterwards put in bags of one hundred- 

 weight each for tho European market; some planters kiln-dry it. Pimento is imported 

 almost entirely from Jamaica, hence it is sometimes called Jamaica pepper. See AJ.L- 

 SPICE; PIMENTO. 



EUXAIRITE. An ore of silver found at the Skrikerum copper-mine in Sweden. 

 According to Berzelius, it consists of selenium, ^G'; silver, 38'93 ; copper 23'05 ; earthy 

 matter, 8'90 ; carbonic acid, &c., 3'12. 



EUXiYTIXTE. A silicate of bismuth, found in small tetrahedral crystals, with 

 other bismuth ores, at Schneeberg, and at Braunsdorf in Saxony. 



EUPKORBIACEJE. The Spurge family. Most of the plants of this order 

 abound in a milky acrid juice in which the peculiar principle of the plant resides. 

 It contains a great number of plants which are either useful or dangerous to man. 

 The Jatropha yields the manihot or cassava. The Ricinus is the castor-oil tree ; tho 

 Croton, Cascarilla, and Box, and the caoutchouc varieties, are included in this vast 

 family of plants, which are found in all parts of the globe, and said to number 2,800 

 species. 



EUPHORBIUM, commonly called from Euphorbius, is an acrid resin obtained 

 from Euphorbia officinarum (Linn.), and imported from Western Africa. It is used 

 only medicinally. 



EUPHOTIBE. A rock composed mainly of saussurite and smaragdite, or some 

 other variety of diallage. It has been cut and polished as an ornamental stone. 



EUFIONE. A fluid first discovered by Reichenbach in wood-tar. All tho 

 properties of eupione agree with tho indifferent hydrocarbons found in Boghead 

 naphtha. Eupione is so indifferent to the action of acids, that it may bo repeatedly 

 treated with concentrated oil of vitriol, or fuming nitric acid, without any action 

 taking place. Its density varies with the boiling point, from 0'633 to 0740. It is 

 said to be contained among the products of tho distillation of rape-oil. Thoro is no 

 doubt that these hydrocarbons will, eventually, be of great value in tho arts. C.Q.W. 

 See NAPHTHA, BOGHEAD. 



EURITE. A name applied to some fulstonos in consequence of their easy fusi- 

 bility compared with homstones, which they often greatly resemble in general cha- 

 racters. 



EURYAHTGIUIVI SUIVXBUIi. The Sumbul plant, a native of Bucharia. See 



EVANSITE. A hydrous phosphate of alumina from Hungary, named by Mr. D. 

 l r orl>es after the late Mr. Brooke Evans, of Birmingham, 



EVAPORATION 1 (Eng. and Fr. ; Abdampfen ; Abdunttcn, Gor.) is the i 

 1-y which any substance is converted into, and carried off, in vapour. Though iiv. 

 camphor, and many other solids evaporate readily in dry air, wo shall consider, at 

 present, merely tho vaporisation of water by heat artificially applied. 



Tho vapour of water is an clastic -fluid, whoso tension nnd density depend upon the 

 temperature of the water -with which it is in contact. Thus tho vapour rising from 

 water heated to 165 F. possesses an elastic torn; capable of supporting a column of 

 mercury 10'8 feet high; and its density is such that 80 cubic feet of the vapour contain 



