books.google.de - Appendix. On the preparation of artificial colouring matters with the products extracted from coal tar, by M.E. Kopp: p. [99]-108....http://books.google.de/books/about/The_chemistry_of_gas_lighting.html?hl=de&id=sac_AAAAYAAJ&utm_source=gb-gplus-shareThe chemistry of gas lighting