DETERMINATION OF IRON IN GLASS SAND*

The 0-phenanthroline method for the colorimetric determination of iron has been adapted to the analysis of glass sand. The sample taken for analysis was decomposed by treatment with HF and H₂SO₄, followed by fusions of any insoluble material with Na₂CO₃ and finally with K₂S₂O₇. An aliquot was then adjusted to the proper pH by a simple procedure, the iron reduced by hydroxylamine hydrochloride, the 0-phenanthroline complex formed, and the transmittancy of the solution measured spectrophotometrically. The method is simple and rapid, and compares favorably in precision and accuracy with other available methods.     

EFFECT OF IRON ON FLUORESCENCE IN GLASS*

The mechanism of fluorescence as it occurs in a uranium glass when irradiated with ultraviolet light is discussed with special reference to factors affecting both the intensity and spectral distribution of the fluorescence. The destructive effect of iron on the fluorescence of the glass is discussed and is illustrated by spectral absorption curves and by recorded fluorescence spectra. Conclusions based on these data indicate that iron not only absorbs a large portion of the exciting radiation, thereby decreasing the fluorescence emission, but also re-emits this absorbed radiation in the infrared, thus bringing about the infrared quenching of the fluorescence. Iron also causes an electrical disturbance around the fluorescing centers and is apparently capable of preventing the absorption of exciting radiation by these centers, further decreasing the intensity of fluorescence. A slight shift of the fluorescence spectrum toward shorter wave lengths is brought about by the presence of iron and is evidence of a weakening of the binding forces within the glass.     

EFFECT OF STORAGE CONDITIONS ON WEATHERING OF COMMERCIAL GLASS CONTAINERS*

Important factors in the weathering of commercial flint glass containers were determined by the storage of empty bottles, capped and uncapped, of ten different compositions for periods up to thirteen months at (1) 100°F., 80% relative humidity, (2) 12OoF., 15% relative humidity, and (3) normal room conditions. The effect of storage was determined by visual inspection, tests of the alkali extraction by water at elevated temperatures and photomicrographs of the weathered surfaces. The results obtained indicate that the most important factor in the weathering conditions used is the humidity. Although the weathering produced depends on several factors, the important weathering effect of high humidity may be significantly controlled by the chemical composition of the glass. Storage for the periods used at low relative humidity or at normal room conditions was relatively ineffective for weathering any of the bottles tested. Photomicrographs of representative weathered internal and external bottle surfaces are shown. A microscopic examination of these surfaces revealed the presence of calcite     

FACTORS INFLUENCING AUTOCLAVE CHEMICAL DURABILITY TESTS OF GLASS CONTAINERS*

To secure reproducible results with the chemical durability test in which distilled water is used as the leaching medium, the distilled water must be prepared with special care because certain impurities, of which copper is the most important, are present in small quantities and exhibit a marked effect on alkalinity values. Other impurities, such as lead, iron, sodium silicate, and sodium carbonate, which may be found occasionally in distilled water, do not have as great an effect as copper on alkalinity values. The temperature at which the leaching is carried out has a much greater effect on the test than the length of the test period.     

EFFECT OF IRON OXIDE ON MELTING OF GLASS*

The addition of small amounts of iron oxide (0.1 to 0.2%) to soda-lime-silica glass batches exerts a profound influence in increasing the output of glassmelting tanks as well as in favoring the production of higher quality glass. The color produced by this addition, moreover, is not objectionable for many uses of the ware. The accelerated melting rate probably is the result of a chemical effect of iron oxide in the batch and a physical property possessed by such glass to absorb radiation from the flames more efficiently. Attempts to measure these effects were made by rioting the melting rate of glasses which contain varying additions of iron oxide and by determining the temperature gradient that exists in glass when it is melted in a miniature tank. The presence of iron oxide aids melting and fining in crucible melts at 1200°C., but no effect was observed at higher temperatures. The measurement of temperature gradients in a pot holding 45 lb. of glass and heated by flames passing over the glass surface showed that the temperature gradient increases with iron oxide content.     

THE WEATHERING OF GLASS CONTAINERS1

Stability in storage is a requisite of commercial glass. A white film or surface spotted with white patches is frequently observed on glass that has been in storage for some time. These weathering effects can be produced artificially by several methods which are given. Several factors, including humidity, have been found to influence the rate at which weathering takes place. Dipping in hydrochloric acid before packing retards weathering and paper properly used in packing is effective in decreasing the tendency to weather. Three classes of weathering effects are given and illustrated with microphotographs. Experiments show that continued boiling removes the weathered surface. The products of weathering consist of crystals of soluble salt or salts, principally sodium carbonate, and an insoluble film. The lime, soda, and silica are found to have the same relative values in the weathered material as in the original glass, with the addition of certain amounts of carbonate, moisture, and dirt and organic material. Weathering is largely dependent on solubility. Glass showing the greatest resistance to weathering proves equally resistant to action of water at temperatures and pressures above normal. Condition of surface appears to influence the solubility. Alumina increases the resistance of glass to weathering. Sodium carbonate may exist in glass after manufacture and assist in weathering.     

GLASS CONTAINERS1

For centuries glass bottles have been recognized as superior containers. At present over 4000 different sizes and shapes are being made and the industry is in a state of rapid extension. Glass containers possess the advantage of being sanitary and permitting the contents to be seen. Recently the laboratory of the Glass Container Association has tested 180 lots of beverage bottles. Some of the better types, or those approaching the champagne style, were found to withstand an end crushing pressure of from 8000 to 12000 pounds, a transverse pressure of from 800 to 1800 pounds, a hydrostatic pressure of from 400 to 1600 pounds, and an impact of a fifty-pound hammer falling from 2 to 6 feet. Similar tests are in progress on other types of containers and on the closures employed. Troubles due to alkalinity are of rare occurrence.     

METALLURGICAL STUDY OF CAST IRON FOR GLASS MOLDS*

Research data are reported on the susceptibility of cast iron to cracking when it is used in molds for processing glassware. An accelerated test was run to produce cracking in a shorter time than would occur in the production of glassware. The results from this test indicate that sand-cast iron is more resistant to cracking than chill-cast iron of the same composition. The alloyed chill-cast irons, however, cracked less severely than the unalloyed iron. An annealing heat-treatment of these irons increased resistance to cracking, whereas a spheroidizing heat-treatment reduced resistance. A maximum resistance to cracking together with the ability of the iron to take a high polish apparently may be obtained by using an annealed, chill-cast alloy iron containing chromium, nickel, and molybdenum. Such iron is more susceptible to cracking than a sand-cast iron of the same composition, but the latter type is incapable of a sufficiently high polish and usually has an open, porous structure.     

EFFECT OF COMPOSITION AND TEMPERATURE ON SOLUBILITY OF IRON OXIDE IN GROUND-COAT ENAMEL GLASS*

The solubility of iron oxide in ground-coat enamel glasses at various temperatures was studied by adding varying amounts of ferric oxide to the milled enamel and giving the mixture a heat-treatment to acquire uniformity without devitrification at the desired temperature. The iron oxide solubility was obtained by finding the breaking point in the curve for iron oxide versus index of refraction. The frit solubilities were obtained at 1400°, 1600°, 1800°, and 2000°F. with variations in Na₂O, B₂O₃, A1₂O₃, CaF₂, CaO, F₂, SiO₂, COO, NiO, MnO₂, BaO, and MoO₃. Data are given on a number of commercial frits.     

EFFECT OF IRON OXIDE ON PROPERTIES OF SODA-DOLOMITE LIME-SILICA GLASS*

In two base glasses, the first containing 16% of sodium oxide, 10% of dolomite lime, and 74% of silica, and the second with 14% of sodium oxide, 12% of dolomite lime, and 74% of silica, iron oxide was systematically substituted for (a) Na₂O, (b) CaO·MgO, and (c) SiO₂ in amounts of 1, 3, and 5%. The effects of these substitutions on such properties as liquidus temperature, viscosity, deformation temperature, fiber softening point, density, coefficient of expansion, and the resistance of the glasses to dilute acid and distilled water, arc presented.     

THE DETERMINATION OF IRON IN GLASS SAND1

Data are presented in tabular form showing the determination of iron in the Bureau of Standards Sample of Glass Sand, No. 81. The electrometric titration method, the H₂S reduction method, and the gravimetric method are described in detail.     

ANALYSIS OF SELENIUM IN GLASS*

A new method for the determination of selenium in glass is reported. It comprises fusion of the sample with sodium carbonate, dissolution of the melt in sulfuric acid, distillation of the selenium as selenium tetrabromide from a sulfuric-hydrobromic acid solution, and titration of the distilled selenium by the iodide-thiosulfate method. The method is rapid, accurate, and precise and recovers all forms of selenium. The recommended procedure is outlined.     

OXIDATION-REDUCTION EQUILIBRIA IN GLASS BETWEEN IRON AND SELENIUM IN SEVERAL FURNACE ATMOSPHERES*

This study has been limited to the reactions between iron and selenium in soda-lime and potash-soda-lime glasses melted in atmospheres of air, nitrogen, and carbon monoxide. Glasses containing selenium and iron, together and singly, were melted in the several atmospheres. and their spectral absorption curves between 350 and 1000 mμ were obtained. An analysis of these curves shows that under neutral or slightly oxidizing conditions selenites react with ferrous iron as follows: This reaction leads to an increase in red and brown and a decrease in blue colors. The decolorizing action of selenium may be explained by this reaction because the colorless selenite ion oxidizes the more colored ferrous ion to the less colored ferric ion, arid the increase in the red elemental selenium color physically compensates as a complimentary color for the remaining unoxidized ferrous ion. The results show that it is not necessary to postulate the formation of ferrous selenium to explain the color changes. The results also show that under reducing conditions the principal reaction is      

高铁颜色玻璃的研究与生产

介绍了铁氧化物的吸热特性及光谱特征;重点论述了高铁颜色玻璃生产时配料工艺、熔化工艺、锡退工艺的调整。     

STUDY OF PHOTOLUMINESCENCE IN GLASS*

The influence of composition and temperature on the fluorescence of glasses containing uranium and glasses containing cuprous oxide and stannous oxide was investigated. Secondary cations reduce the fluorescence of uranium in the glasses studied, depending to a certain extent on the electrostatic conditions they produce in the glass structure. The intensity of fluorescence as well as the structure of the spectrum diminishes in the order of phosphate, silicate, and borate glasses of equivalent compositions, which shows that fluorescence is favored by increase of oxygen in the glass structure without increasing the interfering secondary cations. Raising the temperature greatly diminishes the intensity of the fluorescence as well as the structure of the spectrum of glasses containing uranium. The fluorescence of the glasses containing cuprous oxide and stannous oxide as activators seems to be favored by increase in lime and increase in silica. These glasses possess appreciable phosphorescence, which appears to be enhanced by increase in silica and decrease in lime. A peculiar property of this type of luminescent glass is a maximum which it exhibits in its fluorescence-temperature relation-ship. There are indications that electrons are set free from the excited centers (copper atoms or small groups of copper atoms), which wander about in the glass structure.     

STUDY OF DIFFUSION IN GLASS*

An introductory study was made of diffusion into glass from salts, with silver nitrate as the chief source of diffusing particles. The optimum test conditions were a temperature of 900°C. and a test time of 108 hours. The results noted were (1) effect of time, (2) effect of temperature on the distance of diffusion, (3) variation of silver concentrations in the glass with the distance of diffusion, and (4) a check of Fick's law of diffusion. The concentration gradient of silver from a diffusing interface was determined with the use of a spectrograph and corresponding particle sizes with an ultramicroscope. In addition to the silver nitrate, a number of other salts were tested at several temperatures. The development of Liesegang rings was noted in some of the samples. The nature of diffusion in glass was deduced from the results.     

IRON OXIDE IN ENAMEL GLASS AS DISSOLVED FROM THE METAL BASE*

The iron oxide content of an enamel glass was measured by the use of a predetermined curve representing iron oxide versus the index of refraction. It was found that the iron oxide content of the glass adjoining the interface between the enamel and the iron base rises sharply in the early stages of firing to a value close to the solubility limit of the glass after which it gradually falls to a constant value. The iron content at the surface remains low until that at the interface decreases, whereupon the surface concentration correspondingly increases. The cobalt additions resulted in a lower iron content in solution at the interface, but they increased the dendrite content of the glass. A decrease in the cobalt content resulted in an opposite effect. There was a direct relation between the amounts of cobalt and dendrites and the adherence. The effects of temperature and thickness of application are given, and the results are discussed.     

VARIATIONS OF REFRACTIVE INDEX OF GLASS WITH TIME AND TEMPERATURE IN ANNEALING REGION*

The refractive index of a rapidly cooled fiber of borosilicate glass was found to increase according to the equation, 1/(N₆–N) – 1/(N₆–N₀) =At, where t is time, N₆ is equilibrium index, and A is a constant at constant temperature. Index data were plotted according to this equation to determine, graphically, values of N₆ and A for several temperatures between 914° and 1060°F. Values of N₆ for temperatures from 1060° to 1180°F. were determined by prolonged heating of the glass at each 20° interval. The change of A with temperature was found to be well represented by the equation, log A=K/T+C, where T is the absolute temperature and K and C are constants.     

DETERIORATION OF GLASS IN TROPICAL USE*

Glass deteriorates rapidly in tropical regions with a high relative humidity. Transparency decreases due to the growth of deposits of corrosion products, chemical decomposition of the surface layer to produce pits or holes, or contamination of the surface by organic material. The processes involved in tropical deterioration are similar to the chemical reactions of glass and water in other environments.     

THE FLOW OF GLASS IN TANKS*

The paper deals with the flow of glass in tank furnaces. Reference is given to previous work on this subject. Experimental data are given for water and other liquids and the physical principles are discussed. Illustrations indicate the direction of flow in a glass tank.