740 GUANO 



The mode of producing grey dyes upon cotton has been explained in the articles 

 CALICO-PRINTING and DYEING. 



GREYWACXE. GrauwacJce. A German term, used to designate the coarse 

 slaty strata of the transition rocks. It is now employed to designate the brecciated 

 beds which occnr in those formations. 



GRINDING AND CRUSHING MACHINERY. See DRESSING OF ORES. 



GRINDSTONE. Grindihg-stones or grit-stones are varieties of sandstone, most 

 of those which are celebrated being obtained from the sandstones and millstone grits 

 of the coal-measures. Mr. Knight describes the best known varieties, which are the 

 following : 



Newcastle Grindstones. These abound in the coal districts of Northumberland, 

 Durham, Yorkshire, and Derbyshire. They are selected of different degrees of coarse- 

 ness and density, according to the work for which they are required. 



Bilston Grindstone is a similar description of stone, of great excellence, of a lighter 

 colour, much finer, and of a very sharp nature, and at the same time not too hard. 

 It is confined to a small spot of limited extent near Bilston in Staffordshire, where it 

 lies above the coal. 



WicJcersJey Grindstones. These are obtained from a village about nine miles east 

 of Sheffield, and are much used for the finer description of edge-tools. 



Sheffield Grindstone. A hard, coarse gritstone, used for grinding large files and 

 the like ; it is obtained from Hardsley, about fourteen miles north of Sheffield. 



Devonshire Baits are obtained near Collumpton. 



Yorkshire Grit and Congleton Grit are other varieties from which grindstones are 

 manufactured. 



Burr Stones. These are very celebrated ; they are found at La Ferte-sous-jouarre 

 (Seine et Maine), and are said to be unequalled for grist-mills. The combined rough- 

 ness and hardness of this tertiary quartz-deposit give it immense advantages. The 

 stones formed of this rock are usually pieced, which renders them very expensive. 



Artificial grindstones have been successfully made of late by Eansome's method of 

 manufacturing artificial stone. They are said to form excellent and economical sub- 

 stitutes for the natural grindstones. 



GRXS-PERIiE. The name given by the French dyers to a grey produced by 

 the action of sulphuric acid on aniline violet. It is much used in dyeing silk. See 

 ANILINE. 



GRIT. A peculiar hard sandstone. See MILLSTONE GRIT. 



GROATS, EIYIBDEN. When oats are deprived of their integuments, they are 

 called groats, and when these are crushed, they are known as Embden groats. Oat- 

 meal is prepared by grinding the grains. 



GROS DE NAPLES. A plain silk fabric woven of organzine silk, prepared 

 with much neatness and care. 



GROSSUliARXA. Gooseberry -gar net. See GARNET. 



GROUND IVY. Nepeta Glechoma. The leaves of this plant were formerly 

 thrown into a vat with ale, to clarify it and give it a flavour. 



GROVE or GROOVE. A mining term in Derbyshire. ' The mine, or work 

 that a man is employed in. Hence it is, if a question be asked, Where is Tom to- 

 day ? He is gone to the groove, he is at the groove. Sometimes it is used for the 

 shaft, and mines are commonly called groovers.' Hooson's Miner's Dictionary. 



GROWAN. A local term applied in Cornwall to granite in an imperfect state, 

 either through decomposition, or irregular formation. It is said that the term is some- 

 times applied to the solid granite. We have never heard it so used, and the miners 

 and the quarrymen draw a well-defined line between a granite and a growan. 



GUAXACU1VX. (Ga'iac, Fr. ; Guajaharz, Ger.) Both the wood and resin are 

 imported; they are used medicinally. It is known that, after the discovery of the 

 New World, when the first syphilitic diseases showed themselves in Europe, the 

 origin of which was erroneously ascribed to Santo Domingo, the guaiacum wood was 

 considered as specific against this disense. The historian Ilerrera informs us that 

 one pound of the wood was at that period paid in Spain with seven piastres. The 

 gum which exudes from the wood, and possesses, as it may bo conceived, the medi- 

 cinal qualities in a much higher degree, is now valued at Id. per pound. 



GITAN1NE. C'H S N 5 2 (C^KPO). An organic base, found by linger in guano. 

 Guano contains about 6 por cent of it. 



GUANO. This extraordinary excromentitious deposit of certain sea-fowls, which 

 occurs in immense quantities upon some parts of the coasts of Peru, Bolivia, ;m<l 

 Africa, has lately become an object of great commercial enterprise, and of ii!t--n>" 

 interest to our agricultural world. More than thirty years ago it was exhibit 

 talked of merely as a natural curiosity, but the quantity imported into England 

 alone rose from 30,000 to 350,000 tons (in 1858), the value of which was csti- 



