An octagonal ink cake by the same maker in the National Palace Museum, Taibei, is illustrated by Ts'ai Mei-fen, 'Wenfang yong ju', Usable Objects from the Scholar's Studio, The National Palace Museum Monthly of Chinese Art, no. 11, February 1984, p. 5.
The name of the inkmaker, Wang Jinsheng, does not appear to be recorded although it is possible that this may be the same (or related to) Wang Jinsheng, who supplied the Qing Court with ink as recorded in Zhongguo Lidai Renming Dacidian, A Biographical Dictionary of Historical Chinese Dignitaries, Part I, p. 1140. As suggested by the two characters, Yuci, inks of this type were made as Imperial gifts.
Compare with an almost identical ink cake with the same maker's mark, sold in New York, 22 March 2000, lot 42.