Richardson then went to the University of Giessen, where, under Prof Justus von Liebig, he carried out researches on the composition of coal and the use of lead chromate in organic analysis, gaining a doctorate (Ph.D.).
Practical improvements introduced into the process by George Burnett soon after led to the annual importation of several thousand tons of Spanish hard lead into the Tyne district, where it was purified.
John Percy brought forward evidence that Richardson was not the inventor of this process, quoting a letter from James Leathart, and stating that a patent for it was granted to Walter Hall in 1814.
Henry Watts replaced Ronalds as Richardson's collaborator for the last three of the five parts; and the book, which was recognised as a standard work, was incorporated by Charles Edward Groves and William Thorp in their Chemical Technology.
The reports contain a record of a large and carefully conducted series of experiments; the conclusions were opposed to those of Sir Henry Thomas de la Beche and Lyon Playfair, on whose recommendation Welsh steam coal had been exclusively adopted by the navy.
Richardson published fifteen independent papers and six in collaboration with E. J. J. Browell (a fellow lecturer at the Newcastle school of medicine, and partner), John Lee, Pelouze, Sopwith, and Robert Dundas Thomson, on chemical questions.