722 EOTCH 



loses its colour, like the manganate, but at very high temperatures it behaves dif- 

 ferently. When its colour has once been destroyed by a moderate heat, it does not 

 become either green or blue by farther heating with access of air. The whole be- 

 comes at once of a greyish-brown. The finest barytes green is formed by calcining 

 the manganate of baryta. Rosenstiehl's process the fusion of hydrate of baryta with 

 chlorate of potash and peroxide of manganese yields an inferior colour. 



ROSE OJJt. See OTTO OF ROSES. 



ROSE-PINK. A coarse and common colour, much used in the cheaper kinds of 

 paper-staining, and for distemper painting. It is prepared by saturating chalk with a 

 strong infusion of Brazil-wood. 



ROSETTA WOOD. An East-Indian wood of a lively red-orange colour, and 

 handsomely veined with darker marks. It is occasionally used in fine cabinet-work. 



ROSEWOOD. This well-known wood, which has long been fashionable for 

 drawing-room and library furniture, is a native of the Brazils, the East Indies, the 

 Canary Islands, and some parts of Africa. The best rosewood comes from Rio de 

 Janeiro, and is believed to be yielded by a species of Dalbergia. 



1 Rosewood is a term as generally applied as iron-wood, and to as great a variety 

 of plants in different countries, sometimes from the colour, and sometimes from the 

 smell of the woods. The rosewood of Bahia and Rio Janeiro, called also Jacaranda, 

 is so named, according to Prince Maximilian, as quoted by Dr. Lindley, because 

 when fresh it has a faint but agreeable smell of roses, and is produced by a mimosa in 

 the forests of Brazil. Mr. G. Loddiges informs me it is the Mimosa jacaranda.' 

 Holtzapffel. 



Rosewood is imported in large slabs, or the halves of trees, some of these logs pro- 

 ducing as much as 1501. when cut into veneers. 



ROSIN, or common resin. The residue of the process for obtaining oil of tur- 

 pentine. While liquid it is run into metallic receivers coated with whiting to pre- 

 vent adhesion, and from these laded into casks. See TUBFENTINE. 



Rosin imported in 1873. 



Cwts. Value 



From France 61,793 32,954 



,, United States of America . . 888,025 434,085 



Other countries .... 5,971 4.569 



Total . . . 955,789 471,608 



Rosin imported in 1874, 1,066,681 cwts. ; value 442,700. 



When the distillation is not carried too far, the product is called yellow rosin ; it 

 then contains a little water. The heat being continued, the water is expelled, and 

 transparent rosin is the result. 



If the process be continued up to a point short of producing the decomposition of 

 the rosin, it acquires a deep colour, and becomes brown or black rosin, sometimes 

 called colophony. 



Rosin is insoluble in water, but soluble in alcohol, ether, and the volatile oils. It 

 unites with wax and the fixed oils by heat, forming the Emplastruin rosinee of the 

 London Pharmacopoeia. 



Rosin is employed in common varnishes ; it is united with tallow in the preparation 

 of common candles. It has been proposed to employ rosin as a source from which gas 

 might be obtained. The experiments made were not, however, of so successful a kind 

 ns to warrant the general adoption of the process. 



ROSIN OZXi. By distillation rosin separates into rosin oil and tar. (See TAR.) 

 This oil is a mixture of four carbides of hydrogen : C U H" ; C'H 12 ; C M H 18 ; and C 2U H". 

 The rosin oil, which distils over at about 300 Fahr., is sometimes used in the arts 

 as a substitute for the oil of turpentine. The part which boils at 464 Fahr., called 

 retinole, C 32 H 18 , enters into the composition of some printing inks. 



ROSIN TIN. A pale-coloured oxide of tin with a resinous lustre is so called by 

 the miner. 



ROSOIiANE. See ANILINE VIOLET. 



ROSOLIC ACID, discovered by Rung6, and more fully examined by HugoMiiller. 

 Obtained by exhausting the crude carbonate of lime from the gas-purifiers with a 

 dilute boiling solution of carbonate of ammonia ; evaporating to dryness, ammonia 

 is evolved, and a dark resinous body separates, which is the crude rosolic acid. The 

 crude acid thus obtained is purified by conversion into a lime salt, and the acid is 

 again liberated by acetic acid. 



BOTCH, or ROCHE. A local term used by quarrymen and miners in South 

 Staffordshire for a soft and friable sandstone. H.W.B. 



