Sesquioxide densities

The oxide of lead which is used in the manufacture of crystal, is sot the protoxide commonly known as massicot, and represented by the formula Pb O, but minium, which is a sesquioxide, Pba 0 for, as Bahru el remarks, one may depend on tho latter net being mixed with metallic lead, which almost necessarily happens with the massicot of commerce. The object of employing oxide of lead in this kind of glass is to increase the density, and, consequently, tho refractive power, which gives the glass a peculiar lustre or brilliancy. 

Figures 7 and 8 show that the linear decay predicted by Equation (10) is followed consistently by the two catalysts, A and C. The rule of linear decay was followed with 11.8% and 7,9% of average deviation for catalysts A and C, respectively. For calculating a, the rate of decay in (10), values of s 1,95 and pvc 4,72 g/cu,cm. were taken. The latter is the density of vanadium sesquioxide (S3V2) which Is usually considered the prevalent product in the vanadium deposit.

Cobalt Sesquioxide, Co203, results when cobalt nitrate is gently heated to 180° C.4 It is a black, amorphous powder, of density 518. Hydrogen begins to reduce it at 182° C.5 It may be regarded as the cobalt salt of cobaltous acid, namely, cobaltous cobaltile, CoCo03. 

Hydrated Palladium Sesquioxide, PdjOj.aiHjO, is conveniently prepared9 by electrolytic oxidation of palladous nitrate. This is effected by cooling a concentrated solution to 8° C-, and electrolysing with a current density of 0-5 amperes per sq. cm. It may also be obtained by ozonising a solution of palladous nitrate. 

Chromic sulphide is a broAvnish-black, lustrous amorphous powder, of density 3-538 at 14° C. When heated in air it gives sulphur dioxide and chromium sesquioxide, Avhile in hydrogen it yields chromous sulphide. It is attacked and oxidised by nitric acid, aqua regia, and fused potassium nitrate. Compounds of chromic sulphide with sulphides of other metals haA-e been described. Regarding chromic sulphide as the thioanhydride of thiochromous acid, H2Cr2S4, these compounds may be described as thiochromites. 

Chromium Disilicide, CrSij, has been prepared by the method described for the previous compound, a higher percentage of silicon being used. It has also been obtained by heating a mixture of chromium sesquioxide and charcoal with excess of silica in an electric furnace. By the first method the silieide is obtained as a grey crystalline powder by the second, as long, grey, lustrous needles, only obtained free from silicon with difficulty. Density 4-393. It is decomposed by hydrofluoric acid. 

The crystal structure of La202C2 determined from three-dimensional X-ray diffraction on a twin crystal is of monoclinic symmetry, space group C/2m (Seiver and Eick 1976). The lattice parameters are a = 7.069(8) A, b = 3.985(4) A, c = 7.310(9) A and p = 95.70(6)° the calculated density is 5.41 gcm". In this structure, the lanthanum atom has four oxygen and four carbon atoms situated in a distorted bicapped trigonal prismatic arrangement. Interatomic La-O distances range from 2.392(8) to 2.823(9) A and La-C distances from 2.86(1) to 3.11(1) A. The carbon atoms are present as C2 units with an interatomic C-C distance of 1.21(3) A. Oxygen atoms are tetrahedrally coordinated, as in the sesquioxide. 

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