738. GREENSAND 



GREEN 1 I-EAB ORE. An arsonio-phosphato and chlorido of load. Seo 

 PYROMORPHITE. 



GREEN IiINNETS. A miner's name for green lead-ore or pyromorphito. 



GREENOCXITE. Native sulphide of cadmium. It occurs in small, but very 

 perfect and brilliant, short hexagonal crystals, in a porphyritic greenstone, on preh- 

 nite, and associated with oalcito. It has been found in a railway -cutting at Bishops- 

 town, near Paisley, and at Bowling, near Old Kirkpatrick. It was first observed by 

 the late Lord Greenock, afterwards Earl Cathcart, hence its name. See CADMIUM. 



GREEN PAINTS. (Couleurs vertes, Fr. ; Grunc Pigmente, Gor.) Green, 

 which is so common a colour in the vegetable kingdom, is rare in the mineral. There 

 is only one metal, copper, which affords in its combinations the various shades of 

 green in general use. The other metals capable of producing this colour are, chro- 

 mium in its sesquioxide, nickel in its hydrated oxide, as well as its salts, the selonate, 

 arsenate, and sulphate ; titanium in its prussiate ; and some of the salts of uranium. 



GREEN PIGMENTS. Under the name of ' green cinnabar,' Vogel described a 

 new colour. Prussian blue is dissolved in oxalic acid, chromate of potash is added to 

 this solution, which is then precipitated with acetate of lead. The precipitate, well 

 washed, dried and levigated, gives a fine green powder. By varying the proportions 

 of the three solutions, different shades of green may be produced. Another method 

 has been given by Dr. Eisner. Make a solution of yellow chromate of potash and 

 another of yellow prussiato of potash ; then mix the two, dissolve separately in water 

 some acetate of lead and iron, and add this solution to the others. By precipitating 

 the first two solutions by the third, a green deposit is obtained, the tint depending on 

 the proportions employed. 



Green pigments are prepared also by the mixture of yellows and blues ; as, for ex- 

 cimple, the green of Rinman and of Gellert, obtained by the mixture of cobalt-bluo 

 and flowers of zinc ; that of Barth, made with yellow lake, prussian blue, and clay ; 

 but these paints seldom appear in the market, because the greens are generally extem- 

 poraneous preparations of the artists. 



Mountain green consists of the hydrate, oxide, or carbonate of copper, either 

 factitious or as found in nature. 



Bremen or Brunswick green is a mixture of carbonate of copper with chalk or lime, 

 and sometimes a little magnesia or ammonia. It is improved by an admixture of 

 white lead. It may be prepared by adding ammonia to a mixed solution of sulphate 

 of copper and alum. 



Frise green is prepared with sulphate of copper and sal-ammoniac. 



Mittis green is an arsenate of copper, made by mixing a solution of acetate or sul- 

 phate of copper with arsenite of copper. It is in fact Schecle's green. 



Sap green is the inspissated juice of buckthorn berries. These are allowed to fer- 

 ment for 8 days in a tub, then put in a press, adding a little alum to the juice, and 

 concentrated by gentle evaporation. It is lastly put up in pigs' bladders, where it 

 becomes dry and hard. See COLOURS, Table of. 



GREENS AND. The term 'Greensand' applies to the strata lying between the 

 Chalk and the Wealden deposits. They are of marine origin, as is denoted by the 

 presence throughout their entire thickness of sea-shells, and are divided into an upper 

 and lower series, separated by a stratum of clay, called gault. The Upper Greenland. 

 which underlies the Chalk Marl, is composed chiefly of calcareous sand in the lower, 

 and of sandstone and layers of chert (a compact flinty rock) in the uppermost part. 

 The sandstone affords a good and durable building stone. The chert is well adapted 

 from its toughness for making roads, and the sandy portion, in addition to its useful- 

 ness as a component of mortar, furnishes an excellent agricultural soil, from the calca- 

 reous matter it contains, in addition to the large percentage of soluble silica entering 

 into its composition, which sometimes amounts to more than 40 per cent. In 

 Sussex, Surrey, and Kent, the land based upon the Upper Greensand is known by 

 the name of malm, and produces the greater part of the hops for which those counties 

 are celebrated. In the neighbourhood of Godstono and Merstham, in Surrey, ex- 

 tensive quarries are driven into the hills, at the base of the chalk downs, for the 

 purpose of procuring the soft and chalky stone which occurs there in the higher 

 portion of the Upper Greonsand, for which there is a large demand in London, 

 for cleaning door-steps and stonework in the fronts of houses, under the name of 

 hearthstones. A plentiful supply of pure water is borne up by the impermeable st rat i. 

 forming the uppermost part of the Upper Greensand, which finds its way out of the 

 ground near the base of the Chalk, and forms the sources of many streams and 

 rivers. 



The Lower Greensand consists of alternations of sands, sandstones, and clays, which 

 are often very ferruginous, so much so sometimes as to constitute a siliceous oro of 

 iron, as is the case of Seend in Wiltshire, and Shotover in Oxfordshire. Tho 



