726 RTJTILE 



iron, brass, or other metal surfaces. For this purpose they take : Gutta-percha, 10 Ibs. ; 

 mutton-suet, 20 Ibs. ; beef-suet, 30 Ibs. ; neats -foot oil, 2 gallons ; rape oil, 1 gallon. 



These materials are melted together until thoroughly dissolved, and then coloured 

 with a small portion of rose-pink ; oil of thyme, or other perfuming matter, being at 

 the same time added. When cold, the composition is ready to be applied by rubbing 

 upon the metallic surfaces which require protection. 



RTTTACEJE. The only plant in this natural order which is employed in manu- 

 facture is the false Dittany (Dictamnus fraxinelld). Perfumers obtain from the flowers 

 of this shrub a very odorous distilled water, which is used as a cosmetic. It is also 

 employed in giving flavour to some liqueurs. 



R.UTE, in mining. Used in some lead mines to distinguish very small strings of ore. 



RUTHENIUM (Symb. Ku. ; At. wt. 52'11). After osmium, ruthenium is the 

 most refractory metal known. It requires a very extreme heat to melt the smallest 

 quantity. When melting, there is formed the oxide of ruthenium, which is volatilised, 

 and which smells something like osmic acid. When removed from the flame, ruthenium 

 is blackish-brown on the surface, and is brittle and hard like iridium. It is only dis- 

 tinctly separated from this last metal by its density, which is obviously half that of 

 iridium. The purest ruthenium obtained has a density of 11 to 11'4. 



To prepare the metal mix the osmide in fine powder with 3 parts of binoxide of 

 barium and 1 part of nitrate of baryta, and heat them to redness in a clay crucible for 

 an hoar. The black friable mass which remains is powdered with great care and 

 introduced into a flask in which has been previously mixed 20 parts of water and 10 

 parts of ordinary muriatic acid. The flask must be placed in cold water to avoid 

 the elevation of temperature which would ensue from the violent reaction which 

 takes place. This operation should be conducted under a good chimney to avoid the 

 escape of the osmic-acid vapour into the laboratory. 



When this reaction is finished, 1 part nitric acid is added, and then 2 parts ordinary 

 strong sulphuric acid. The flask is now well shaken, and the sulphate of baryta is 

 allowed to deposit. The supernatant liquid is then poured off, the precipitate is 

 washed by decantation, and the liquid and the washings are distilled together in a 

 tubulated retort, until about a fourth of their volume of a liquid very rich in osmic 

 acid has passed over. The red liquor which is left in the retort is evaporated to a 

 small volume, 2 or 3 parts of sal-ammoniac in small pieces are added, and a small 

 quantity of nitric acid. The whole is now evaporated to dryness at the temperature 

 of boiling water. A crystalline violet-black precipitate remains in the capsule, which 

 is treated with a small quantity of water partly saturated with sal-ammoniac, and washed 

 with the same solution until it is no longer coloured. The insoluble salt left (chloro- 

 iridate of ammonia containing ruthenium) is heated by degrees to redness in a 

 porcelain crucible. The mixture of iridium and ruthenium thus obtained is fused in 

 a silver crucible with an equal weight of hydrated potash and twice its weight of 

 nitre, and when cold the rutheniate of potash is dissolved out with cold water ; the 

 solution, which is yellow, is decomposed by means of carbonic or uitric acid, and the 

 precipitated oxide of ruthenium is strongly calcined in a charcoal crucible. The 

 ruthenium is then reduced in the apparatus before described. Iridium and ruthenium 

 present many analogies; their coloured reactions are the same, and the oxide of 

 iridium dissolves in a mixture of nitre and potash. 



Kuthenium forms with zinc an alloy which will burn in the air ; it crystallises in 

 hexagonal prisms. With tin there is formed an alloy RuSn 2 , which crystallises in 

 cubes as beautiful in their form and lustre as crystallised bismuth. Deville and 

 Debray on the Platinum Metals. 



KTJTXXiS. Native oxide of titanium. 



Eutile occurs in granite, gneiss, mica-slate, and Syenitic rocks, and occasionally in 

 granular limestone. It has sometimes been met with in specular iron. The way in 

 which it occurs in masses of quartz or felspar, the acicular crystals being imbedded, 

 ia very curious. The following localities are given by Dana : ' Brazil affords acicular 

 crystals in limpid quartz ; also occurs in Arendal in Norway ; Sau-alpe, Carinthia ; in 

 the Urals ; in the Tyrol ; at St. Gotthard ; at St.Yrieix, in France ; Krummhennersdorf 

 near Freiberg ; in Castile, in geniculated crystals, often very large. At Ohlapian in 

 Transylvania, Nigrinc in pebbles; in large crystals in Perthshire; at Cairngorm, 

 Scotland ; at Craig Cailleach near Killin, and in Bengloe ; in Isles of Burray, Shet- 

 land. A variety from Karingsbricka in Sweden contains a small percentage of 

 chrome, and is the titane oxyde chromifere of Haiiy. Rough octahedrons, reticulated 

 within, from Brazil, are supposed to be pseudomorphs after anastase.' Besides 

 these, Dana gives at least twenty localities in America. 



The oxide of titanium is employed for a yellow colour, in painting porcelain ; and 

 it is often employed to give the requisite tint to artificial teeth. Eutile is so named 

 from the Latin rutilus, which signifies a shining red.' 



