GREY DYE 739 



ferruginous sands form the iron-sand of Dr. Smith. The Lower Greensand, also, con- 

 tains beds of Fuller's Earth, which are -worked at Reigato, and they furnish a durable 

 and useful building stone, known by the name of Kentish Rag, and quarried exten- 

 sively in the neighbourhood of Maidstone. 



The term ' Greensand/ though applied to deposits of considerable thickness, is, in fact, 

 only strictly applicable to certain minor portions of them, which are marked by the 

 presence of minute grains of green silicate of iron (the glauconite of American mine- 

 ralogists), These impart a colour to the beds in which they occur, which has given 

 the name to the entire formation. H.W.B. See CHERT ; FIRESTONE ; GATJLT. 



GREEN, SCXXEEZiE'S. An arsenite of copper. See COPPER. 



GREEN* SXiOXE. Ulva latissima, the broad green larer. See ALGJB. 



GREENSTONE. ' Greenstone is a dark and heavy blackish green or brownish 

 rock, consisting of felspar and hornblende ; it usually has a crystalline texture, but is 

 sometimes compact.' Dana. The term has been loosely applied by geologists to a 

 number of rocks of similar general appearance, but of different mineralogical composi- 

 tion. See DIABASE ; DIORITE. 



GREEN UXTRAXtXARXXE. This is artificially prepared in France and Ger- 

 many, and employed, instead of the arsenical greens, for printing upon cotton and 

 paper. See ULTRAMAHINE. 



GREEN* VXTRXOZi. Sulphate of iron, or copperas. See IRON, Sulphate of. 



GREXSEN. A rock composed of a granular mixture of quartz and mica gene- 

 rally lithia-mica in fact, a granite without felspar, or a mica-schist in composition, 

 but without foliation. It is frequently associated with tin-ore in the mining districts 

 of Saxony and Bohemia. 



GRENADA COCUS or GRENADXX.X.O. This wood, imported from the 

 West Indies, is called red ebony by the French cabinet-makers. 



GREY ANTI*FsIO WH*. The native trisulphide of antimony. See ANTIMONY. 



GREY COPPER. A native di sulphide of copper. See COPPER. 



GREY* 3>YE. (Teinture grise, Fr. ; Grraufarbe, Ger.) The grey dyes, in their 

 numerous shades, are merely various tints of black, in a more or less diluted state, 

 from the deepest to the lightest hue. 



The dyeing materials are essentially the tannic and gallic acid of galls or other 

 astringents, along with the sulphate or acetate of iron, and occasionally wine-stone or 

 crude tartar. Ash-grey is given for 30 pounds of woollen stuff, by one pound of gall 

 nuts, \ Ib. of wine-stone, and 2 Ibs. of sulphate of iron. The galls and the wine-stone 

 being boiled with from 70 to 80 pounds of water, the stuff is to be turned through the 

 decoction at a boiling heat for half an hour, then taken out, when the bath being re- 

 freshed with cold water, the copperas is to be added, and, as soon as it is dissolved, the 

 stuff is to be put in and fully dyed.. Or, for 36 pounds of wool ; 2 pounds of tartar, 

 \ pound of galls, 3 pounds of sumach, and 2 pounds of sulphate of iron are to be 

 taken. The tartar being dissolved in 80 pounds of boiling water, the wool is to be 

 turned through the solution for half an hour, and then taken out. The copper being 

 filled up to its former level with fresh water, the decoction of the galls and sumach is 

 to be poured in, and the wood boiled for half an hour in the bath. The wool is then 

 taken out, while the copperas is being added and dissolved ; after which it is replaced 

 in the bath, and dyed grey with a gentle heat. 



If the grey is to have a yellow cast, instead of the tartar, its own weight of alum 

 is to be taken ; instead of the galls, one pound of old fustic ; instead of the copperas, 

 f of a pound of Salzburg vitriol, which consists, in 22f parts, of 17 of sulphate of 

 iron, and 5| of sulphate of copper ; then proceed as above directed. Or the stuff 

 may be first stained in a bath of fustic, next in a weak bath of galls with a little 

 alum ; then the wool being taken out, a little vitriol (common or Salzburg) is to be 

 put in, previously dissolved in a decoction of logwood ; and in this bath the dye is 

 completed. 



Pearl-grey is produced by passing the stuff first through a decoction of sumach and 

 logwood (2 Ibs. of the former to 1 of the latter), afterwards through a dilute solution 

 of sulphate or acetate of iron ; and finishing it in a weak bath of weld containing a 

 little alum. Mouse-grey is obtained when, with the same proportions as for ash-grey, 

 a small quantity of alum is introduced. 



For several other shades, as tawny-grey, iron-grey, and slate-grey, the stuff 

 must receive a previous blue ground by dipping it in the indigo vat ; then it is 

 passed first through a boiling bath of sumach with galls, and lastly through the 

 same bath at a lower temperature, after it has received the proper amount of solution 

 of iron. 



For dyeing silk grey, fustet, logwood, sumach, and elder-tree bark, are employed 

 instead of galls. Archil and annotto are frequently used to soften and beautify the 

 tint. 



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