W A C 



WAD 



mical analyfes can be expefted to agree, as they muft vary 

 with the proportions of the prevailing ingredient. A fpeci- 

 men of aniygdaloidal wacke analyfed by Withering gare 



Silex - - ^i 



Alumine - - 13 



Lime . . 7 



Iron - - 17 



Wacke, is fufible, melting into a vitreous flag, the colour 

 of which will vary according to tlie prevailing ingredient 

 which compofe this rock. This mineral muil not be con- 

 founded with another rock called grey wacke or grau wacce. 



Wacke, Grey, or Grey IVacie, or IV'acce, a name given by 

 later geologifts to a very extenfive feries of rocks, the mem- 

 bers of which differ greatly from each other in compofition, 

 ftrufture, and appearance : indeed the name has been ap- 

 plied fo indefinitely, that it has occafioned much confufion 

 and obfcurity in geological defcriptions, and we confider the 

 introduftion of the term as having tended greatly to retard 

 the progrefs of practical geology. A great variety of very 

 different rocks, the nature of which was not precifely known, 

 have been claffed with grey wacke, which ferved as a name 

 to conceal ignorance under the veil of fcientific arrangement. 

 Some geologifts reftricl the term to thofe rocks which have 

 a bafis of clay-flate ; others extend it to all the coarfe grit 

 ftones which contaui rounded and angular fragments united 

 by a cement of any kind ; and the French, under the name 

 of pfammitc (which they have recently introduced), comprife 

 along with grey wacke all the coarfe fand-llones of the coal 

 formation. In all extenfive formations of clay-flate, the 

 upper beds will frequently contain particles of quartz, flinty 

 flate, and other minerals, which fometimes give them a coarfe 

 and fometimes a granular appearance; and even in the midft 

 of beds of pure flate, beds of this coarfe flate frequently 

 occur, which, when they have a fchiftofe tlrufture, are the 

 grey wacke flatcs of the German geologifts. Mr. Jamefon 

 defines grey wacke to be a kind of fand-ftone very different 

 from any of thofe that occur in the fletz rocks. It is com- 

 pofedof grains of fand, which are of various fizes, and fome- 

 times even approach in magnitude to rolled malfes. Thefe 

 are connedled together by a bafis of clay-flate, and hence 

 this rock derives its grey colour and folidity. Thefe frag- 

 ments are quartz, a kind of indurated clay-flate, or flinty 

 flate. 



When the fandy particles of grey wacke become fo fmall 

 as fcarcely to be perceptible by the eye, it acquires a flaty 

 ftrufture, and then forms grey wacke-flate, which, he 

 adds, bears a ftriking fimilarity to clay-flate. " This flate 

 has feldom a greenifli or yellovvifli colour, as is the cafe with 

 primitive flate, but is nfually blucilh, afh and fmoke grey. 

 It does not fhew the filvery continuous Inllre of primitive 

 clay-flate, but is rather glimmering, which originates from 

 fcales of mica. Quartz fcarcely occurs in it m layers, but 

 ufually traverfes it in the form of veins. It docs not con- 

 tain cryftals of filfpar, fchorl, tourmaline, garnet, or horn- 

 blende, nor beds of garnet, talc, chlorite-flate, or magnttic 

 iron-ftone. Grey wacke-flate contains petrifaftions, parti- 

 cularly three varieties tiiat border on grey wacke. 



"Grey wacke and grey wacke-flate alternate, and are dif- 

 tinftly ftratifted ; but t!ie Itratificalion of the former is more 

 diftinft than that of the latter. They fometimes alternate with 

 beds of tranfiiion lime-llone, trap, flnity flate and coal-blende. 

 This rock is unconunonly produftivc of nietals, not only in 

 beds but in veins, wliich latter are'frequently of great mag- 

 nitude. Almoft all tlie mines of the Hartz are lituatcd in 

 grey wacke. The whole of the lead veins of Lead llflls 

 and Wanlockhead, in Scotland, are fltiialed in grey wacke." 



It was for a long time contended, that the killas or flate 

 of Cornwall was grey wacke : it is now confidered as a true 

 clay-flate, rcfting immediately on the granite of that diftrift. 

 Grey wacke was, by the Wernerian geologills, regarded as 

 partly of ehemical and partly of mechanical formation ; the 

 fragments which it contained were fuppofed to be the debris 

 of older rocks ; but on this hypothelis it muft appear ex- 

 traordinary that thefe fragments fliould be fo limited in their 

 kind, and tliat granite, fyenite, gneifs, and the other primi- 

 tive rocks, fhould rarely, if ever, occur in it. 



The hypothcfis of the meclianical formation of grey 

 wacke is now abandoned by its former fupporters ; and it 

 is even contended, that the rounded maffes in many conglo- 

 merated rocks and in fand-ilones have been formed chemi- 

 cally, and that plum-pudding ftones are in many inflances 

 chemical formations, as thefe ftones fometimes graduate into 

 the adjoining rocks, and the nodules themfelves not unfre- 

 quently alfo graduate into the rock in which they are im- 

 bedded. 



The occurrence of grey wacke, imbedded in what has 

 been called primitive flate, offers a further proof that the 

 origin of this rock, in fuch inftances, is not derived from the 

 debris of pre-exifting rocks, but is more analogous to the 

 formation of porphyries, though the procefs by which it 

 has been folidiiied did not allow the imbedded particles or 

 nodules to take a regular cryftalline form. From what has 

 been ilated, it will appear, that under the name of grey 

 wacke may be claffed a great variety of rocks, fome ap- 

 proaching to the nature of porphyry, others to plum-pud- 

 ding ftone; others again, wiiere the fragments are imbedded 

 in a pafte, refemble coarfe grit-flones, vvhilft many rocks of 

 clay-flate, which are not perfeftly homogeneous, may be 

 alfo claffed with grey wacke, thougii they nearly refemble 

 primitive flate. Whilft fuch latitude is allowed to the ap- 

 plication of the term, it is obvious that no geological de- 

 fcription can convey accurate information where it is intro- 

 duced, unlefs it be accompanied with a definite account of 

 the compofition of the rock to which this name is given ; and 

 geologifts would do well to reftrift its ufe, or to banifh it 

 altogether from the nomenclature of rocks. 



WACKENITZ, in Geography, a river which runs from 

 Ratzebnrg hike into the Trave at I-ubeck. 



WACKMOYJUST, a town of Dirmah ; 12 miles S. of 

 Ravnangong. 



WACSAW, a town of America, on the line which di- 

 vides North from South Carolina, where, in the year 1781, 

 700 Britifh troops, under the command of lieutenant-colonel 

 Tarleton, came up with a party of Virginian troops, under 

 colonel Burford, amounting to 300 men ; the latter being 

 fnmmoned to furrender refuted, and a niofl bloody engage- 

 ment enfued, when few of the Americans efcaped ; 53 pri- 

 foners only were taken, except the \vo\uided. 



WADAN, or Zala, a town of Fe/.zan, in the road 

 from Tripoli to Mourzouk ; 1 60 miles N. of Mourzouk. 

 N. hit. 29° 5y'. E. long. 15° 12'. 



WADD, or Wadding, in Gunnery, a ftopple of paper, 

 hay, ftraw, old rope-yarns, or tow, rolled firmly into the 

 form of a ball, and forced into a gun upon the powder, to 

 keep it clofe in the chamber ; or put up clofe to the lliot, 

 to keep it from rolluig out, as well as to prevent the pow- 

 der, wlien fired, from dilating round the fides of the ball, 

 by Its windage, as it pafles through the chale, which would 

 conliderably diminilh the effort of llie powder. From fome 

 experiments recited in the Military Diftionary, it is in- 

 ferred, that tlie judicious ramming of a little wadding over 

 the powder adds .ibout one-fourth part of the whole erieft. 



Waup, or ll'dd, in Mineralogy, a name given to a fpecies 



of 



