Note 135 — Appendix. Cement for Earthenware. Restorations.

Instead of potassium cyanide, I have made experimental use of the much more readily fusible potassium sulphocyanide. This converts the iron compounds into iron sulphide, which is easily got rid of. The sulphide which still adheres to the iron and imparts a not unpleasing blackish colour to the object appears to be stable.

The rest of the treatment is similar to that above described. Having so far only experimented with a few specimens I am not yet in a position to offer any judgment as to the practicability of the process. (Author, 1904.) [For practical objections to this method, which we do not consider satisfactory owing to the instability of the products resulting from the reaction, and the difficulty in removing them by the subsequent washing, see Milbauer, “Zeit. f. anorg. Chem.” XLII. 1904, p. 433 (“Journ. Chem. Soc.” Abstracts, i. 121), where it is stated that treatment of Fe₂O₃ at 400°C. leads to the formation of K₂Fe₂S₄. Transl.]