VEI 



VEL 



club-moss. Tt is highly inflammable, 

 and is used for pyrotechnical purposes. 



VEGETABLE WAX. A wax-like sub- 

 stance procured from several species of 

 Myrica, one species of which {gale), from 

 the uses to which this substance has been 

 devoted, has been named the Tallow- 

 shrub or Candleberry-tree. The wax is 

 found, in some cases, on the berries, in 

 others on the cones or catkins. Another 

 remarkable plant of this kind is the Ce- 

 roxylon andicola, a Wax Palm of the 

 American Spaniards. 



VEGETATION, SALINE. A kind of 

 crystalline film which shoots up spon- 

 taneously from the edges of a solution of 

 crystallizable matter, as salt, camphor, 

 &c. 



VEGETO - ALKALIES. Alkaloids. 

 A class of bodies obtained from the vege- 

 table kingdom, containing nitrogen, hav- 

 ing the properties of the basic or metallic 

 oxides, and forming salts with acids. Of 

 this class are quinine, strychnine, vera- 

 trine, &c. 



VEGETO-SULPHURIC ACID. An 

 acid procured by treating ligneous fibre 

 with sulphuric acid. 



VEINS, MINERAL. Cracks or fis- 

 sures in rocks filled up by substances 

 different from the rock, which may be 

 either earthy or metallic. Veins are 

 sometimes many yards wide ; and they 

 ramify or branch off into innumerable 

 smaller parts, often as slender as threads, 

 like the veins of an animal. Inconsider- 

 able veins, which diverge from the prin- 

 cipal, are called slips ; and those masses 

 of ore which are of considerable magni- 

 tude, but of no great length, are called 

 bellies, or stockworks. 



M. Came characterizes eight succes- 

 sive groups of veins and slides in Corn- 

 wall. The oldest are tin veins (lodes), 

 underlying (dipping) to the north, 

 ranging nearly e. and w. by compass. 

 The second class consists of tin veins, 

 underlying to the south, ranging e. and w. 

 nearly (by compass). The third includes 

 east and west copper veins. The fourth 

 are diagonal (or contra) veins, ranging 

 N.w. aipd S.E., and yield copper. The 

 fifth includes cross courses, ranging n.nw. 

 and s.sE., and rarely yielding metal, ex- 

 cept lead. A sixth group includes ' cross 

 flukans' (clay veins), ranging nearly n. 

 and s. An eighth includes ' the slides,' 

 "Which are formed of soft clay, and cut 

 through all the others. 



VEINS OF PLANTS. The ramifica- 

 tions of the petiole among the cellular 

 361 



tissue of the leaf are called veins, and 

 the manner of their distribution is termed 

 venation. 



1. The principal vein, or that which 

 forms a continuation of the petiole and the 

 axis of the leaf, is called the midrib or 

 costa ; if other veins similar to the mid- 

 rib pass from the base to the apex of the 

 leaf, such veins have been called, though 

 incorrectly, nerves, and a leaf with such 

 a distribution of veins has been called a 

 nerved leaf. 



2. A leaf is said to be three, ox five, or 

 otherwise nerved, if the so-called nerves 

 all proceed from the base of the lamina; 

 it is also said to be triple, quintuple, &c. 

 nerved. If the veins diverge from the 

 midrib towards the margin, ramifying as 

 they proceed, such a leaf is called a 

 venous or reticulated leaf. 



3. Dr. Lindley adopts the following 

 terms :— 1. The largest veins given off 

 from the midrib on each side, are the 

 primary veins ; each of these forms a 

 curve, and anastomoses with the back of 

 the next primary; the curved portion 

 being called the curved vein. 2. Between 

 the curved vein and the margin, other 

 veins, proceeding from the curved veins, 

 with the same curved direction, and of 

 the same magnitude, occasionally inter- 

 vene : these may be distinguished as 

 external veins. 3. The margin itself and 

 these last are connected by a fine net- 

 work of minute veins, which may be 

 called marginal veinlets. 4. From the 

 midrib are generally produced, at right 

 angles with it, and alternate with the 

 primary veins, smaller veins, which may 

 be called costal veins. 5. The primary 

 veins are themselves connected by fine 

 veins, which anastomose in the area be- 

 tween them ; these veins, when they im- 

 mediately leave the primary veins, are 

 proper veinlets, and, where they anasto- 

 mose, common veinlets. 6. The area of 

 parenchyma, lying between two or more 

 veins or veinlets, is called intervenium. 



VELO'CITY (velox, quick). The velo- 

 city of a body is the rate of its motion, or 

 the degree of quickness with which it is 

 moving. The velocity of a body is uni- 

 form, when it moves through equal 

 spaces in equal times, and it is then 

 measured by the space described in a 

 certain unit of time, as a second ; when 

 the velocity is variable, it is measured by 

 the space which would be described in 

 the said time if the motion were con- 

 tinued uniform for that time. 



1. Velocity, absolute and relative. The 

 R 



