The Tangpin 湯品 "A classification of tea boiling" is a book on the quality of water for boiling tea. The author of this book is unknown, as well as the date of compilation. Sixteen different types of waters are discerned in the book and are individually discussed. The book begins with the discussion of three different methods to boil various tea waters (jianfa 煎法), then explains three methods to to pour out the water (zhufa 注法), goes on with presenting five various types of pots and bowls, and ends by analyzing five types of fuel to heat the water. The book was presented to the compilers of the imperial collectaneum Siku quanshu 四庫全書 by Vice Censor-in-chief (fu duyushi 副都御史) Huang Dengxian 黃登賢 from his own library, but it was not included in this collection and is rarely to find elsewhere, mostly because of its trivial character.
Source: Li Xueqin 李學勤, Lü Wenyu 呂文鬰 (1996). Siku da cidian 四庫大辭典, vol. 2, p. 1863. Changchun: Jilin daxue chubanshe.