Herbert Insley

DETERMINATION OF THE SOURCE AND MEANS OF PREVENTION OF STONES IN GLASS

The microscopic characteristics of different crystalline materials occurring as stones or lumps in glass are described and photomicrographs of stones originating from devitrification of the glass, incomplete solution of batch constituents, and incorporation in the glass of refractory wall material are reproduced. Methods of determining the location in the glass-making system of the source of stones, using microscopic as well as other methods, are given. Means of prevention or elimination of the stones are suggested.

THE SERVICE OF REFRACTORY BLOCKS IN A SMALL EXPERIMENTAL GLASS TANK1

Tests to determine the relative resistance of various types of refractories to the action of flowing molten glass were made in a small laboratory glass-melting furnace similar in shape and in operation to commercial scale, continuous glass tanks. The results of tests made in nine runs of the furnace, each run continuing for approximately 30 days, are given. The resistance of the refractories to glass attack apparently does not depend entirely upon chemical composition and porosity of the refractories, but is probably related also to (1) the size of pores, (2) the relative composition of grog and bond, and (3) the degree of adherence between particles in the refractory.

THE FAILURE OF THERMOCOUPLE PROTECTION TUBES IN GLASS MELTING FURNACES1

The unusually rapid failure of thermocouple protection tubes when used in glass furnace atmospheres has been found to be due to reaction of the volatilized alkalis in the atmosphere with the aluminum silicates of the tube. Failure of the tubes is due either to differential thermal contraction between the outer reaction layer and the inner unaltered layer of the tube on cooling or to actual corrosion and dripping away of the tube. It is suggested that the use of a much higher percentage of alumina and lower percentage of silica in the tubes may prevent failures from this cause.