AN APPARATUS FOR MEASURING THE ABRASIVE HARDNESS OF GLAZES1

An apparatus for measuring the resistance to abrasion, or scratching, of glazes and possibly other materials is described. It provides, essentially, for the wearing away of the surface by means of standard cement sand, which is allowed to run through a funnel adjusted to deliver a definite amount of sand for a given time interval, and to strike the inclined surface of the test piece after falling a fixed distance. The loss in weight under this treatment is assumed to bear a definite relation to the resistance to abrasion.     

THE WITCHERY OF GLAZES1

A paper showing the extent of research possible in glazes and the fascination of the work in that field. It is implied that the general chemist has little to offer to shorten the road that must be followed and that the work is reward enough for the labor involved. It is shown that the artistic temperament functions in this work along with the scientific temperament.     

THE EFFECT OF FURNACE ATMOSPHERES ON THE QUALITY OF CERTAIN TYPES OF GLAZES1

A research sponsored by the American Gas Association was begun at Rutgers University in January, 1929. One phase of this research is the determination of the effect of furnace atmospheres on glazes, By maintaining carefully controlled conditions all variables were eliminated except that of atmosphere. Tests were made in many atmospheres using several different glazes. These atmospheres were formed either of the individual products of combustion, of combinations of gases which simulated actual furnace conditions, or of the products of combustion of city gas.     

NOTE ON THE EFFECT OF TIME ON THE DRYING SHRINKAGE OF CLAYS1

The drying shrinkage or clays were studied to determine how quickly different types can be dried and to note whether or not the time of drying influences the amount of shrinkage. Three shales, two ball clays and one fire-clay were tested and the following conclusions reached: (a), drying time depends largely on water content; (b), the structure of the clay is an important factor; (c), the amount of total shrinkage is proportional to the water content; (d), the amount of total shrinkage is not influenced by the rapidity of drying.     

NOTE ON THE RATIONAL ANALYSIS OF CLAYS1

Several feldspars, muscovite, biotite and quartz, as well as diaspore clay and kao linite, in fairly pure state, were severally subjected to the procedure of “rational analysis” of clays. It was shown by analysis of the residues and solutions obtained:

• 1 That all the feldspars were attacked to a greater or less extent
• 2 That the micas were attacked more than the kaolinite
• 3 That kaolinite was not wholly decomposed by the treatment
• 4 That diaspore clay was not approximately decomposed by the treatment
• 5 That the amount of decomposition of all the substances depends to a considerable extent on the time and temperature of treatment.

As a result of these conclusions, it would not be possible to draw any conclusion as to the clay substance content of a particular clay from the results of a rational analysis.     

THE INFLUENCE OF CHEMICAL COMPOSITION ON THE PHYSICAL PROPERTIES OF GLAZES*

This paper presents some preliminary work on the study of the factors affecting fit of ceramic bodies and glazes. From the experimental work on 118 glazes and glasses, a method is outlined for calculating from the chemical composition of the glaze, approximate values of the tensile strength, Young's modulus of elasticity, and the mean linear coefficient of expansion of the glaze in the temperature range from 25°C to the lower limit of the critical range.     

NOTE ON THE ACID RESISTANCE OF ENAMELED COOKING UTENSILS1

Apparent segregation of the constituents of an enamel under the influence of gravitation. —Experiments with trial pieces with poured samples, and with enameled ware of various mfgr's. showed that the surface of the layer of enamel which is uppermost during firing and cooling is readily attacked by acid, thus indicating, apparently, that the more soluble materials tend to rise to the top of the melt. It is therefore recommended that enameled kitchen utensils be fired in an inverted position. In the discussion by Bryan A. Rice a series of similar experiments are described using small shallow cups. Quantitative tests failed to show any difference in acid resistance and it is suggested that the author's results were due to the nature of the gases in contact with the enamel surface or to volatilization. In his reply the author accepts this explanation of his results.     

A STUDY OF THE CONSISTENCIES OF RAW TERRA COTTA GLAZES1

For measuring consistencies of glazes, a method was used based on the conception of glazes as plastic materials. A normal glaze thinned during the entire period of testing, being attended by a large decrease in yield value and a moderate increase in mobility. Use of an aged clay slip as a source of clay did not change the plastic properties or aging characteristics of the glaze. Heating a freshly milled glaze resulted in a consistency comparable with that developed by aging a normal glaze for a month. Water solubilities of glaze materials were determined as well as character and concentrations of soluble salts in mill liquors and P_H values of mill liquors. Solution of salts was progressive over a period of time and increasing alkalinity was probably the cause of spontaneous thinning. Gum arabic in proper amount was found to stabilize glaze consistency satisfactorily. Effects of acid, alkali, and water additions to gum-bearing and gumless glazes were studied.     

绿色透明釉的研制

采用铅硼釉为透明釉的基础釉,氧化铜和氧化铬为着色氧化物,通过分析氧化铜、氧化铬、添加剂、保温时间对透明釉呈色的影响,借助于偏光显微镜对其析晶性能进行观察。结果表明：氧化铜和氧化铬的比例为1：1时釉呈现翠绿色;氧化镁的加入量为2%-3%有利发于发色;保温时间小于15min不会析出铬金星。     

A GRAPHICAL REPRESENTATION OF THE MOLECULAR FORMULAS OF CERAMIC GLAZES1

A chart representing average glaze composition, including lead, fritted, Bristol, and porcelain glazes, as plotted against temperature is presented as a means for teaching glaze compositions and for getting a broad view of the constituents of glazes and their variation with temperature. The chart covers the range from cones 015 to 18.     

NOTE ON THE EFFECTS OF FIRING TEMPERATURES ON THE STRENGTH OF FIRECLAY AND STONE WARE BODIES1

The cross breaking strengths, porosities and shrinkages of fire-clay and stoneware bodies were determined after firing to different temperatures. It was found that with one exception, maximum strength was developed by firing to cone 8, even when porosity and shrinkage data showed the bodies to be over or underfired at this temperature. The cause of weakening above cone 8 may be due to the formation of sillimanite. Bodies which develop maximum shrinkage and minimum porosity at cone 8 have a greater ratio of fired strength to dry strength when fired to cone 8, than those which are under or overfired at cone 8.     

NOTE ON THE SOLUBILITY OF ENAMEL FRIT IN MILL WATER1

Methods of determining the solubility of enamel frit in mill water are outlined. Various tests tried show that (1) solution increases as fineness increases, (2) mixing has little or no effect upon solubility, (3) variation of smelter treatment has little or no effect upon solubility, and (4) Na₂O and B₂O₃ will dissolve from dry ground frit proportionately to the fineness thereof.     

NOTE ON THE VAPOR ABSORPTION OF A FIRED EARTHENWARE BODY1

Specimens of an earthenware body fired at three temperatures were placed over a 10% sulphuric acid solution for 36 days and the gain in weight determined. Up to a certain limit of porosity the absorption is proportional to the porosity, but the body with the highest absorption, 20.25% took up a relatively higher amount of water. With an absorption of 8.81%, the maximum amount of water vapor taken up was 0.13%. With 10.8% absorption the water vapor taken up was 0.16 and with 20.25% absorption it reached 0.54%.     

EFFECTS OF BODY COMPOSITION AND FIRING TREATMENT ON SALT GLAZES1

Five synthetic bodies were made up in which the silica, alumina, ferric oxide, and alkalis were varied. Salts were added to these bodies in various amounts; the bodies were dried and fired under carefully controlled conditions and salt glazed under oxidizing conditions at cones 2, 5, and 7 and under reducing conditions at cone 5. The effects of body composition and glazing temperature on the appearance of the bodies are giveu. Reducing conditions during glazing increased the glaze thickness. The maturity of the glaze is more important than the thickness. Devitrification of the glazes is more important than the presence of impurities. Crystals of hematite, acmite, nephelite, and carnegieite were found in the glazes. Firing treatment has a greater influence on glaze character than chemical composition.     

闪光釉闪光机理的研究

闪光釉的特征是对入射光有金属镜面般的反向,研究表明,这种反射是由釉中心（200）晶面平行于釉面的的CeO2晶粒造成的,晶粒的取向程度越高反射越强,闪光釉只有施在相应的底釉上才具有闪光效果。