Search

Author's Note: There seem to he some points which are not clear and some omissions which have caused confusion in the paper1 presented by the writer. Owing to the length of this paper, some data were purposely omitted for the sake of brevity. The writer wishes to thank Professor Lord for bringing these points to his attention and also for permitting this discussion of the preceding paper.

Seven American and fourteen English ball clays were compared in regard to bonding effect, (a) after burning, in a composition containing no fluxes, at cones 5, 8, 10 and 12; (b) in a semi-porcelain body burned to cone 8; and (c) in a vitreous china body burned to cone 11. The English clays developed greater strength in the absence of fluxes. The semi-porcelain and vitreous china bodies containing the imported clays were in general of greater strength than those bodies in which the domestic clays were used, but most of the bodies containing American clays were of good transverse strength.

The paper gives a short review of the soda-recovery methods used in the Kraft process. The tests made to determine the relative merits of different refractories were (1) P.C.E. determinations of soda-refractory mixtures, (2) simulative-service slag tests, and (3) petrographic analyses. Tests indicate that resistance is produced by (1) an impervious crystalline structure, such as soapstone for the low temperatures and electro-cast mullite for the high temperatures, or (2) chemical inertness in contact with soda, such as is found with purer forms of magnesia.