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The desorption of precious metals from the PD and PTD ion-exchange resins, containing S-bonded dithizone and dehydrodithizone as functional groups, is described. Each sorbent was loaded batchwise with individual or combined metals and then treated with excess of various extracting agents (6 M hydrochloric acid, 2 M perchloric acid, ammonium nitrate, sodium thiocyanate, thiourea). Strong retention of some adsorbed metals and instability during the loading and elution stages were found with the PD resin, but a selective separation of palladium and gold from accompanying metals was possible. The PTD resin had superior properties. Unsual effects were detected when elution rates were compared for individual metals and mixtures. While Pd and Pt, loaded individually, were desorbed quantitatively by thiourea, co-extracted Ir(IV) completely inhibited their elution. The regeneration of PTD by special sequences of eluents was utilized for selective chromatographic separation of Pd, Pt, Os, Au and (with restrictions) Ir from each other and also from large amounts of base metals and salts.

A reversible graphite oxygen electrode has been found in molten (K-Na)NO 3 eutectic, saturated with sodium peroxide. The measured emf of −1150 ± 5 mV at 503 K vs Ag|Ag + (0.1 m) and its temperature dependence −0.44 mV K −1 are compared with theoretical values, obtained with thermodynamic data. An independent value of the superoxide disproportionation constant K p = (5.3 ± 0.3) × 10 −2 kg atm mol −1 at 503 K has been obtained. Our equilibrium experiments confirm the results of Zambonin et al .

The solubility of zinc sulphate has been measured and the stoichiometry of its reaction and that of zinc chloride in pure lithium nitrate-potassium nitrate eutectic has been established. Chloride ions were shown to increase the stability of the zinc ions, which reacted as a Lux-Flood acid and precipitated as zinc oxide. Nitrate melts containing sodium peroxide, sodium monoxide and sodium hydroxide caused reaction to occur at lower temperatures. No evidence was found for the formation of soluble zincate ions in the presence of excess base.

Characterization of alumina-supported catalysts required determination of rhodium by atomic-absorption spectroscopy (AAS). Catalysts were loaded with 0.1-2.0% rhodium chloride and calcined at 400 degrees . Rhodium remaining as the chloride was regarded as the soluble form, while that converted into the oxide or bonded to the alumina was regarded as the bonded form. By selective dissolution procedures, soluble rhodium was leached from the substrate and determined by AAS. Total rhodium was determined after the catalyst had been fused with sodium peroxide. Bonded rhodium can be determined by difference or by analysing leached residue. Optimization of AAS conditions, use of spectroscopic buffer solution and elimination of interelement interferences are discussed.

Results are presented of a study of the coadsorption of sodium and oxygen on a Cu{110} surface using HREELS, LEED, and AES for a number of annealing temperatures. A 0.5 L exposure of oxygen at 310 K onto a Cu{110} surface predosed with a saturation coverage of sodium results in dissociatively adsorbed oxygen with a primary vibrational loss feature at 48 meV which is very close to that found for dissociatively adsorbed oxygen on clean Cu{110}. Annealing the Cu{110}/Na/O system to 645 K results in a dramatic shift in the vibrational loss feature to 59 meV which is shown to be associated with a dominant vibrational mode of sodium peroxide (Na 2 O 2 ). LEED measurements also indicate that the 645 K anneal gives rise to a stepped surface with {110} terraces and {111} step faces which are 2.64 A high, corresponding to the exposed edge of a single Cu{110} bilayer. The overlayer unit cell and terraces have dimensions that correspond within 1% to the dimension of the unit cell of a room temperature hexagonal phase of sodium peroxide.

A rapid method for the determination of uranium at nanogram levels in geological and biological materials is described. The method is based on the separation of 23.5 min239U, produced on neutron activation, by solvent extraction with TBP from nitric acid medium in the presence of HF, which prevents interference from Th; a number of other possibly interfering elements were shown to be negligibly extracted. The method is selective and sensitive enough for the determination of nanogram levels of uranium in soils, ores and biological samples. Results for some standard reference materials were in good agreement with certified values.

Rapid atomic absorption procedures are described for determining silicon in typical sulphide and silicate minerals and their mixtures, in ores, and in slags. Two sample decomposition procedures are shown to give solutions which have good longterm stability for silicon and are suitable for use in the atomic absorption finish. The applicability of the given operating parameters for the atomic absorption procedure is confirmed for comparable highly-salted solutions that contain contaminants. Although satisfactory results are obtainable when pure silicon standards are used for comparison, the addition of a predominant sample contaminant to the comparison standard can improve the accuracy and precision of the procedure.

Voltammetric experiments, using rotating graphite and platinum electrodes have been carried out in molten KNO 3 NaNO 3 eutectic containing superoxide ions or saturated with sodium peroxide. The experimental curves are compared with those theoretically predicted on the basis of the assumed simultaneous reactions: The experiments in dilute superoxide solutions confirm the results of Zambonin et al . A value for the superoxide disprorportionation constant has been obtained from the difference of the half-wave potentials, viz K p = 8.1 × 10 −2 kg atm mole −1 at 503 K. The peroxide ions produced according to equation (b) cause Na 2 O 2 precipitate on the electrode, even in unsaturated melts. From the experimental data the oxygen, superoxide and peroxide diffusion coefficients have been calculated to be: D O 2 = 3.8 × 10 −4 s −1 , D O − 2 = 4.4 × 10 −6 cm 2 s −1 , respectively.

A new scheme is proposed for the quantitative recovery of ruthenium and osmium collected in lead. The lead button is parted with perchloric acid in the presence of a little acetic acid, after heating at 160—180°C. Ruthenium remains totally undissolved;some osmium remains insoluble but some volatilizes and is collected in an alkaline solution. Platinum, palladium and rhodium are completely dissolved in the lead perchloric acid solution, and are removed by simple filtration. After fusion of the residue with sodium peroxide, the solution is combined with the alkaline osmium solution, and ruthenium and osmium oxides are distilled from a bromate—sulphuric acid medium, prior to their spectrophotometric determination. The method provides satisfactory recoveries, with relative standard deviations of 1.45% (Ru) and 6 3% (Os).

The reaction of mercury(I) sulphate, mercury(II) sulphate and mercury(II) oxide in pure lithium nitratepotassium nitrate eutectic and in nitrate solutions containing sodium peroxide, monoxide and hydroxide have been studied and stoichiometries derived. The initial major reaction product of mercury sulphates was green schuetteite, HgSO4 · 2HgO, which was then converted to brown HgO, or with excess peroxide or monoxide to an easily hydrolysed mercurate compound. With low base concentrations yellow-white and grey sublimates containing mercury(I) and nitrate, were formed from mercury sulphates of both oxidation states.

The reactions of disaccharides with alkaline hydrogen peroxide were studied under diverse conditions. Treatment of cellobiose, lactose, and maltose with aqueous sodium peroxide afforded, in each instance, the corresponding aldobionic acid, the next lower aldobionic acid 2- O - d -glucopyranosyl- d -erythronic acid, and formic acid. On the other hand, melibiose and gentiobiose afforded the corresponding aldobionic acid, the next lower aldobionic acid, and a 2- O - d -glycopyranosylglycolic acid. The yields of products varied widely with the experimental conditions, especially with the proportions of alkali peroxide and hydrogen peroxide. The reactions with alkali peroxide were slow, but rapid in the presence of hydrogen peroxide with the gradual addition of alkali. The results indicate that degradation of carbohydrates by alkaline hydrogen peroxide takes place by five reaction paths. These are designated the alpha-hydroxy hydroperoxide cleavage-mechanism, the Baeyer-Villiger mechanism, the ester mechanism, the dihydroxy-epoxide mechanism, and a newly proposed peroxy-radical mechanism. The last-named mechanism is more rapid than the others. With an excess of hydrogen peroxide and slow addition of alkali, it results in rapid, stepwise conversion of both reducing and nonreducing saccharides into formic acid. The process begins with formation of a hydroperoxide adduct of the carbohydrate. Reaction of the adduct with hydrogen peroxide affords a peroxy radical and a hydroxyl radical. The peroxy radical decomposes, affording formic acid, the next lower aldose and hydroxyl radical. Hydroxyl radical produced in a chain reaction oxidizes alditols and aldonic acids by reactions analogous to those of the Fenton reagent.

The proposed method for the determination of Re traces includes the following stages: sample decomposition with a mixture of sodium peroxide and sodium carbonate, extraction of rhenium with acetone from 5 M NaOH and spectral determination using ICP excitation. The excitation unit of the spectrometer used is equipped with a watercooled burner. The atomic lines ReI 346.047 and ReI 346.473 nm are used. Detection limits are 25 ng Re/ml and 40 ng Re/ml, (2 σ criterion, aqueous solution). The method is applied to the determination of rhenium in ores and concentrates containing more than 1×10−5% Re (0.1 g/t).

A study of oxygen electroreduction at a bright platinum electrode has been carried out in molten sodium hydroxide at 350°C. Analysis of potentiostatic and potentiodynamic measurements led to the following results: (1) The electroactive species in oxygen-containing NaOH melts at 350°C is sodium peroxide. (2) A general method of quantitative determination of kinetic and mass transport parameters for certain reactions has been described. (3) The mechanism of oxygen reduction in molten NaOH has been suggested. (4) Kinetic and mass-transport parameters characterizing oxygen reduction in molten NaOH have been calculated. (5) The reaction studied seems to be one of the rare examples of relative invariance of the Tafel slope with temperature.

The following cyclic compounds were oxidized at 4° by means of aqueous sodium peroxide in large excess: 2,3,4,6/5-pentahydroxycyclohexanone ( 1 ); xylo -pentahydroxy-2-cyclohexen-l-one ( 2 ); xylo -trihydroxycyclohexane-1,2,3-trione ( 3 ); reductic acid ( 4 ); and ninhydrin ( 5 ). On oxidation, 1 , 2 , and 3 gave carbon dioxide, formic acid, and oxalic acid; in addition, 1 yielded DL -glucaric acid, and 2 and 3 afforded xylaric acid. Compound 4 gave almost equimolecular quantities of carbon dioxide and succinic acid. In addition to a small amount of formic acid, compound 5 gave carbon dioxide and phthalic acid in yields of 92 and 95%, respectively. Reaction mechanisms are proposed.

The oxidation of spectroscopic grade graphite using air or oxygen in molten sodium carbonate was investigated at 900, 1000 and 1050†C. The oxidation rate increased with increasing temperature, increasing oxygen concentration, and increasing graphite surface area but decreased slightly as the reaction air was diluted with increasing carbon dioxide concentrations. At high-graphite loadings, the reaction rate was 0.45 order in oxygen, 0.45 order in graphite surface area with an apparent activation energy (Ea) of 35 kcal/mole and appeared to tend toward a rate limit imposed by the available oxidant in the melt. At low-graphite loadings, the rate was 0.42 order in oxygen, 0.78 order in graphite surface area with E = 32 kcal/mole and appeared to tend toward a rate limit imposed by the available graphite surface area. Virtually no carbon monoxide was observed under the conditions of the experiments. A sequence of reactions is proposed in which sodium peroxide, formed by the reaction of oxygen with sodium carbonate is the active oxidizing species.

A stable isotope-dilution method using resonance ionization mass spectrometry is suitable for the determination of rhenium and osmium abundances and osmium isotopic composition in carbonaceous chondrites and iron meteorites. The chemical procedure involves sodium peroxide fusion, followed by distillation of osmium from sulfuric acid/hydrogen peroxide and subsequent anion-exchange separation of rhenium from the same solution.

A simple neutron-activation method for the determination of rhenium based on a preliminary extractive separation of the latter from molybdenum and tungsten is described. The sample is decomposed with sodium peroxide, a small amount of water is added and the resulting pulp is extracted with pyridine. The extract is evaporated to dryness, the residue is dissolved in water and the solution is passed through a column packed with Dowex 50WX8 in H+ form to eliminate the metal impurities. The HReO4 passed, after neutralization with ammonia, is evaporated to dryness in penals, which then are irradiated with thermal neutrons.

The combustion of sodium pools in air or in mixtures of N2/O2 with low oxygen contents has been studied for initial metal temperatures ranging from 365 to 620°C. The analysis of the combustion products, sodium monoxide (Na2O), sodium peroxide (Na2O2) in the residues and aerosols of Na2O2, and unburned sodium has shown that three successive stages are occurring. During the first stage, the whole surface of sodium pool burns. The only products are thus Na2O in the crust and the aerosols of Na2O2. The combustion rate has been measured for different temperatures, with an initial oxygen ratio of 20, 15 or 10 percent in nitrogen mixture and for three different flow rates of the combustible mixture. During the second stage, burning and extinguished zones coexist. In the latter the formation of aerosols ceases arid the crust monoxide is progressively oxidized into peroxide. This oxidation is the only phenomenon still observed during the last stage. In all cases, some sodium remains unburned, probably due...

A method for the systematic activation analysis of seven noble metals--ruthenium, silver, rhenium, osmium, iridium, platinum and gold--in rocks were developed and examined with radiotracers and irradiated rock samples. After the fusion of the irradiated rock sample with sodium hydroxide and sodium peroxide, 10% sodium sulfide solution is added and rhenium is extracted with pyridine-benzene mixture from 6N sodium hydroxide solution. From the hydroxide-sulfide precipitate fraction, ruthenium and osmium are distilled as tetroxides, silver is precipitated as chloride, gold is extracted with ethyl acetate, and iridium and platinum are extracted with diantipyrylmethane. Each fraction is purified and subjected to the gamma-ray spectrometry. Chemical yields for the elements are more than 60%. Determination limits are given for the seven elements.

Aromatic polyesters containing peroxide groups incorporated in the polymer chains were synthesized by interfacial polycon-densation of bisphenol A, sodium peroxide, and isophthaloyl chloride. Iodometric titration, elemental analysis, and IR spectra showed that the polymers obtained possessed a high peroxide content, even though bisphenol A reacted 80 times faster than Na2O2 with isophthaloyl chloride. Analysis of the polymers by high resolution NMR and degradation of the chains with subsequent gel permeation chromatography measurements showed that the distribution of peroxide groups is random in the case of low peroxide content. Higher peroxide content leads to the formation of peroxide blocks in the polymer as well as greater polydispersity of the polyester fragments formed after degradation of the peroxide links.

A comparison is made of the precision and accuracy of the conventional WO3-gravimetric inductively coupled plasma atomic emission (ICP-AES) determination of macro amounts of tungsten in tungsten ores, concentrates, and alloys. Pure tungsten powders are readily dissolved in hydrogen peroxide. Samples having a complex mineralogical and metallurgical composition are conveniently dissolved by fusion with sodium peroxide and the solution stabilized with the employment of phosphoric acid. For ICP-AES analysis, the use of Sc(II) 361.384 as an internal standard reduces short-term variability by a factor of three, producing data that compare favorably with those obtained by the classical cinchonine-tungstic acid procedure and with those quoted in the literature for NBS 277.

The method of express neutron-activation (NA) determination of Au, Pd and Pt has been developed. The method is based on the quantitative isolation of198Au+199Au and109Pd activities by extraction with organic sulfides. The radiation of109Pd is measured on a thin NaI(Tl) crystal and that of198Au and199Au on a Ge(Li) detector. The calculations of interferences from gold have been performed for various neutron fluxes and various cadmium ratios. Some interferences introduced by other competitive nuclear reactions into the determination of Pt by its daughter isotope199Au are discussed.

Procedures are described for the determination of lead and bismuth in steel and cast iron by atomic absorption spectrometry (a.a.s.). Two alternative decomposition procedures are applied, namely, sodium peroxide fusion in zirconium crucibles and digestion with a nitric—perchloric acid mixture in a Bethge digestion apparatus. The latter technique is preferred. Lead is measured by electrothermal a.a.s. with Zeeman background correction. Bismuth is determined after hydride generation with sodium tetrahydroborate. Calibration is done by standard addition. The sensitivities obtained are 1 μg g−1 for lead in steel and cast iron and 5 μg g−1 for bismuth in white and grey cast iron. The r.s.d, is generally better than 10% for > 10 μg g−1. The method is applied to standard reference steel samples and several specimen cast irons.

Acid—base and redox reactions in binary systems of sodium nitrite and several oxides with different acidity and oxidizing ability have been investigated. Kinetic parameters have been obtained by analyzing thermogravimetric data under a constant heating rate. Sodium peroxide is the main basic species in the nitrite melt. Peroxide ion is disproportionated into oxide ion and oxygen atom in the melt. The activation energy of the formation of peroxide is constant, irrespective of the acidity of oxides, while that of the disproportionation increases with increase in acidity. On the other hand, the species which possess oxidizing ability are sodium nitrite, nitrate and peroxide. The nitrate and peroxide are formed intermediately during the course of the reaction. Below 600°C, the oxidizing ability decreases in the order; peroxide, nitrite, nitrate.

Sweeps samples are often complex mixtures containing from trace amounts to 20% of one or more precious metals distributed in matrices consisting of widely varying mixtures of base metals or their oxides. Three collection procedures are described that are suitable for the isolation of precious metals from base substances. One is based on direct fusion of the sample (high-grade sweeps) with sodium peroxide, and the others on collection of the precious metals by fire-assay techniques using either nickel sulphide or silver. The precious metals are then determined either gravimetrically or by atomic-absorption or plasma-emission spectrometry.

An alternative procedure to the classical fire assay method for determining Pt and Pd in sulfide ores, concentrates, and furnace mattes is presented. A suitable amount of sample is digested with aqua regla and filtered and any remaining gangue is digested with a mixture of HF and HClO/sub 4/. The solution is filtered and the residue fused with sodium peroxide granules. The fused salts are dissolved in a dilute HCl acid solution and all three solutions combined. The resultant solution is passed through a Bio-Rad AG 50W-X8 cation exchange resin in the H/sup +/ form. The chlorocomplex anions of Pt and Pd are not retained by the cation exchange resin while the base metal cations are efficiently removed from the eluent. Pt and Pd concentrations are subsequently determined with an inductively coupled plasma (ICP). Preliminary experiments showing the method's potential expandability to Au are included.

Ziel der Untersuchungen war, einen Beitrag zur Aufklarung der Reaktionsablaufe zu leisten, die in den besonders fur die Entzunderung von hochlegierten Chrom- und Chrom-Nickel-Stahlen benutzten Die Untersuchungen erfolgten an den Metallen Silber, Gold, Platin, Nickel und Eisen und an den Metalloxyden FeO, Fe3O4, Fe2O3 und Cr2O3 in NaOH-Schmelzen bei Temperaturen um 500°C. Besondere Aufmerksamkeit wurde dem Einflus der Gasatmosphare auf die Korrosionsgeschwindigkeit gewidmet. Mit Ausnahme des Silbers ist die Korrosion aller untersuchten Metalle und Oxyde unter Sauerstoff erheblich groser als unter Stickstoff, wobei ein Zusatz von Wasserdampf besonders unter Sauerstoff die Korrosion stark inhibiert. Unter wasserdampfhaltigem Stickstoff ist der Angriff der reinen NaOH-Schmelzen praktisch vernachlassigbar. Nur Silber korrodiert bei Gegenwart von Wasserdampf starker als unter trockenen Gasen. Die Korrosionsprodukte wurden chemisch, metallographisch sowie durch Rontgen- und Elektronenbeugung untersucht. Die geringe Korrosion unter Stickstoff zeigt, das die Reaktion zwischen Metallen bzw. Metalloxyden und der NaOH-Schmelze nicht oder nur recht langsam ablauft. Die beschleunigende Wirkung des Sauerstoffs und die inhibierende des Wasserdampfes deuten darauf hin, das der Natriumperoxydgehalt der Schmelze in den meisten Fallen entscheidend fur die Korrosionsgeschwindigkeit ist. Research on the corrosion of some metals and metal oxides in sodium hydroxide melts The investigations were aimed at contributing to the clarification of reactions encountered in the salt baths specially used for the descaling of high-alloyed chrome and chrome-nickel steels, particularly the Hooker bath. The investigations were carried out on the metals silver, gold, platinum, nickel and iron and on the metal oxides FeO, Fe3O4, Fe2O3 and Cr2O3 in NaoH melts at temperatures around 500°sC. Special attention was paid to the influence of the gas atmosphere on the corrosion rate. With the exception of silver, the corrosion of all the metals and oxides investigated is considerably more intense under oxygen than under nitrogen, and an admixture of water vapour has a strong corrosion inhibiting effect, especially under oxygen. Silver was found to be the only metal to show a higher corrosion rate in the presence of water vapour than under dry gases. The corrosion products were examined chemically, metallographically, and by means of X-ray and electron diffraction. The low corrosion rate under nitrogen shows that the reaction between metals or metal oxides and the NaOH melt takes place rather slowly, if at all. The accelerating effect of oxygen and the inhibiting effect of water vapour indicate that, in most cases, it is the sodium peroxide content of the melt which governs the corrosion rate.

Previous work on solvent-extraction systems for scouring textiles is breifly reviewed. Details of an improved continuous system, based on trichloroethylene, are given including a description of the pilot plant employed in the investigation. A commercial plant now in operation is also described. The trichloroethylene treatment, followed by continuous desizing with sodium peroxide, has been applied to a variety of cotton piece-goods as a preparation for dyeing. Various modifications to obtain a full bleach on cotton have been investigated and, also, the advantages of solvent dewaxing of cotton before conventional bleaching have been assessed. In Part II it is shown that the new continuous solvent-extraction technique can be applied with advantage for scouring several other fibres such as rayon, linen, wool, jute and glass and that, in general, such processes can be carried out continuously in a convenient, safe and economic manner. In addition to cotton, the solvent-extraction method appears of particular p...

A very rapid method for the estimation, of trace amounts of thorium up to 0.01 per cent. or thereabouts even in complex minerals like ilmenite and columbitetantalite has been described. Thorium is collected in an acid solution with phosphates of zirconium and titanium without prior separation of silica, after decomposition of the mineral with sodium peroxide. Thorium is next collected as fluoride with lanthanum as a carrier, precipitated as thorium iodate in potassium iodate-oxalic acid mixture and finally titrated against 0.01 N sodium thiosulphate. Accurate results are obtained within a short time of two working days.

1. An investigation has been made, with the aid of heating curves, of the thermal stabilities and dehydration behavior of the solid phases found in the ternary system NaOH - H2O2 - H2O at O0. namely Na2O2 8H2O and Na4O2 2H2O2 4H2O2, and also of the so-called “sodium hydroperoxido” NaOOH or Na2O2 H2O2 which was synthesized by Tafel's method. 2. The compound Na4O2 8H2O is undoultedly a hydrated form of sodium peroxide. This view is confirmed by the occurrence of endothermic dehydration effects, and by the curves for the dehydration of Na4O2 8H4O4 which pass through the stages Na2O2 8H2O, Na2O2 - 2H2O, and Na2O2 - H2O 3. The compound Na2O2 - 2H2O4 - 4H2O is of lower stability. Its heating curve has a very marked exothermic maximum at 60–65 characteristic of pcthydrate compounds. The temperature at which complete decomposition occurs is the same as the decomposition temperature of Na2O2 - 8H2O. 4. The existing data on the properties of the so-called “sodium hydropetoxide” NaOOH support the view that this compound should be regarded as Na2O2 - H2O2.

A neutron activation procedure suitable for the routine determination of tantalum and hafnium in silicates is described. The irradiated sample is fused with sodium peroxide and leached, and the insoluble hydroxides are dissolved in dilute hydrofluoric acid-hydrochloric acid. After LaF 3 and AgCl scavenges, tantalum and hafnium are separated by anion exchange. Tantalum is obtained radiochemically pure; 233 Pa and 95 Zr contaminants in the hafnium fraction are resolved by γ-ray spectrometry. The chemical yield of the procedure is detemined after counting by re-irradiation. Values for the 8 U.S. Geological Survey standard rocks are reported.

A method is described for the determination of thorium in rocks and minerals which utilizes neutron activation, a radiochemical separation scheme and counting of the thorium-233 β-activity. A discussion is presented of various dissolution procedures used for silicate rocks with the conclusion that a potassium fluoride-pyrosulfate fusion is preferable to acid dissolution or sodium peroxide fusion or sinter. The sensitivity of the method is 10 p.p.b. with a 100-mg sample. Results are given for the USGS standard rocks.

The determination of total or combined sulfur in vulcanized rubber and materials of similar type involves numerous difficulties. This fact is attested by the very large number of methods which have been proposed. All the most important methods involve oxidation of the sulfur, in whatever form it may be present, to sulfate and weighing the latter as barium sulfate. The only essential differences lie in the methods of oxidation employed. The methods which seem to be the most popular at the present time are (1) oxidation of the sample in a Parr bomb with sodium peroxide, potassium chlorate, and sugar; (2) oxidation with perchloric acid and nitric acid, sometimes with the additional use of bromine; (3) oxidation with nitric acid and bromine, followed by sodium carbonate-potassium nitrate fusion; and (4) oxidation with nitric acid-zinc oxide mixture, bromine, and potassium chlorate. Serious explosions have been known to occur with perchloric acid oxidations; hence this method is not so popular at present as the other three. The fusion methods are reliable, but they are time-consuming and therefore not convenient when large numbers of samples must be handled.

Titanium was oxidized anodically in molten sodium nitrite, and sodium nitrite containing 1 mol-% sodium peroxide, at constant cd at 315°C. The anodic oxide film showed rectification, and photocurrent and photovoltage. From these results and the measurements of capacitance of the film, the film is proved to consist of a p-i-n junction. The n-region is in contact with titanium electrode and the p-region is in the outermost layer of the oxide. The i-region is between the n- and p-region. The profile of impurity distribution in the p- or n-region is divided into two parts, a graded and a constant distribution region. The parameters of the junction were calculated. The theory of “Zener breakdown” was adopted for the breakdown of the oxide film; the electric field at the breakdown voltage was about 10 6 V/cm.

The colorimetric method of determining chromium in silicate rocks with diphenylcarbazide has the defect resulting in a distinct tendency for producing slightly lower figures as recognized already. After a thorough study of the method the author pointed out the possible sources for the serious errors, especially for those which give negative results. Thus the oxidation method in an alkaline medium was proposed, which was compared with the widely used old method. The accuracy and reproducibility of this method are not entirely satisfactory but so far it will serve as the most accurate method. The content of chromium in brown coal in Japan determined by this oxidation method with sodium peroxide will be reported in a later communication.

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A procedure is described for the analysis of substances insoluble in acids, or samples containing insoluble substances. After preliminary tests on the original substance, the analysis of the insoluble portion consists of treatment with boiling sodium hydroxide solution, boiling sodium carbonate solution and fusion with either sodium peroxide or a sodium carbonate-sodium nitrate mixture, to bring the various compounds into solution for the application of various spot tests.

In a search for a rapid and accurate method for determining sulfur in rubber it was found that oxidation of the sample by means of sodium peroxide in the Parr bomb is unsatisfactory when the sulfur content of the rubber is low because the samples that can be used for this purpose are too small for accurate results, or, if larger samples are used, the oxidation is incomplete. The use of a mixture of nitric and perchloric acids, as described by Kahane, is also unsatisfactory; but with certain modifications the method may be made to yield very good results, and if fusions are unnecessary, it will save time and labor. The chief modifications recommended are the use of a more dilute solution of nitric acid (equal volumes of the concentrated acid and water), allowing the rubber to dissolve completely on the steam bath before heating more strongly, then heating to gentle boiling until oxidation is complete, and finally destroying the residual nitric acid by means of hydrochloric acid. The use of a large...

Atomic absorption procedures have been developed for the determination of manganese and silicon in ferromanganese and in silicomanganese, chromium and silicon in three different grades of ferrochromium, silicon in ferrosilicon, vanadium in ferrovanadium, titanium in ferrotitanium, boron in ferroboron, and columbium in ferrocolumbium. In most cases a sample is dissolved by a combination of inorganic acids, including hydrofluoric, and using plastic laboratory ware. A sodium carbonate fusion of the acid insoluble portion of ferroboron is employed. A sodium peroxide fusion is used on the acid insoluble portion of one grade of ferrochromium. No separation of elements or reduction of iron concentration is required. All procedures use a nitrous oxide–acetylene flame and a laminar flow burner with any conventional atomic absorption apparatus. Calibration curves were prepared using either U. S. Bureau of Standards samples or analyzed samples of purchased ferroalloys.

A simple, rapid, precise microdetermination of sulphur is described. The substance is decomposed by sodium peroxide in a nickel bomb, the solution of the fused mixture is treated with a cation exchanger, and the sulphate is titrated directly with barium perchlorate according to the method ofFritz andYamamura. The procedure is also applicable to the determination of chlorine, hence simultaneous sulphur and chlorine determinations are possible.

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A method of dissolution of sihceous material has been proposed, together with a method for the subsequent colorimetric estimation of silica as the molybdenum blue reduction compound The finely ground samples are sintered at 500° with powdered sodium peroxide in platinum crucibles, the mixture extracted with water, and acidified. Excess peroxide is removed by oxidation with potassium permanganate. Silica is determined by reduction of yellow silicomolybdic acid with 1-amino-2-naphthol-4-sulphonic acid to the blue reduction compound. Phosphates and iron are masked with tartaric acid The sample solution may also be used for the colorimetric determination of alumina, ferric oxide, and titania

A rapid method for direct determination of total iron in chrome-bearing materials is given. The sample after fusion with sodium peroxide in a nickel crucible is taken into sulphuric acid solution and Chromate is reduced by boiling with ethyl alcohol. Iron is then titrated with mercurous nitrate in presence of a large excess of thiocyanate ion. Other ions which are generally present in chrome-bearing materials do not interfere. Oxides of nitrogen interfere but their effect is eliminated by boiling with urea. A determination can be completed within 20 minutes after opening the sample. The standard deviation has been found to be 0.056.

Preliminary results are reported on the separation of small amount of ruthenium from large amount of molybdenum sulfide and on the neutron-activation analysis of ruthenium in a molybdenite.The chemical yield for ruthenium in the distillation was checked by using a radioactive tracer 106Ru (T1/2=1yr.)and by counting 512KeV and 622KeVγ-rays from106Rh(T1/2=30sec)which is in radiation equilibrium with 106Ru.The procedures for fusion and distillation are as follows. Molybdenum sulfide of about0.1g was fused with sodium peroxide flux(ca.1.5g)in a nickel crusible, and then the black slurry extracted with 20ml of water was dissolved by 40ml of sulphuric acid(1:2)in a distillation flask. The known amount of tracer 106Ru was added to the solution. Osmium was removed by the distillation with hydrogen peroxide(30%). The ruthenium was distilled using 20ml of sodium bromate(20%)and 5ml of concentrated sulphuric acid added in the flask and with the air current through the distillation apparatus. The distillate was absorbed in two receivers, each containing 5ml of 9N sodium hydoxide or 10ml of 5%ethanol-0.2N hydrogen chrolic acid mixture.Comparing the counts of recovered 106Ru with the counts of added one, the distillation yield of 96.5%ruthenium was obtained in a single distillation, and in the doubly repeated 99.5%.In order to determine an amount of ruthenium in the molybdenite quantitatively, 85mg of the molybdenite was bombarded by pile-neutrons, together with a standard sample including 7.9μg of ruthenium.The ruthenium was separated from each neutron-irradiated sample by the same distillation procedures as described above. As a carrier, 216μg of ruthenium was added at the stage of fusion of the neutron-irradiated molybdenite. The distillate for the molybdenite was compared with the one for the standard sample by counting 498KeV γ-rays from radioactive 103Ru(T1/2=40d.)resulted from the neutroncapture on 102Ru. The countings were undertaken using a NaI(Tl)scintillation counter with an anticoincidence guard, along with a 512-channel pulse-height analyser. The concentration of ruthenium in the molybdenite was estimated to be 37×10-9g/g.An isotopic abundance of reagent ruthenium was tentatively measured by a single focusing mass spectrometer with a surface ionization source of a tungsten single filament. About5μg of ruthenium as chrolide was heated to dryness on a tungsten filament in air, and then was pre-heated to dull red in vacuum for two days. The isotopic abundance obtained is reported.

The use of sodium peroxide as a flux in refractory and mineral analysis is reviewed. The rate of attack of sodium peroxide on various types of crucibles is compared and the influence of the impurities introduced into the assay by crucible attack and by sodium peroxide impurity is critically examined. The superior erosion resistance of zirconium crucibles at temperatures exceeding 550° is discussed. It is concluded that many fusion decompositions could be supplanted by sinter decomposition, thereby resulting in a significant reduction in blank levels. Some interferences caused by residual peroxide in extract solutions are also discussed.

A diffractometer equipped with a special furnace was used to record the powder diffraction pattern of Na2O2 over the range 25–550°C. A new phase, Na2O2-II, is stable at high temperatures. The transition temperature was found from diffractometer and separate thermal analysis measurements to be 512 ± 1°C. The thermal expansion coefficient of Na2O2-I, from diffractometer data, was found to be essentially isotropic and linear within the limit of error, and equal to (2·84 ± 0·4) × 10−5 °C−1 (15–460°C). Samples prepared by pouring molten sodium peroxide into liquid air gave a powder diffraction pattern at room temperature which is tentatively identified as that of a third polymorph, Na2O2-Q.

A gravimetric finish has been applied to the semi-micro determination of phosphorus in organic compounds after fusion with sodium peroxide. It has been shown that the precipitate of quinoline phosphomolybdate prepared from 3 mg of phosphorus has the theoretical composition and that, using a special weighing technique, very precise results can be obtained. Two other weighing techniques are described which give results satisfactory for semi-micro work.