In 1897 Haber made a similar trip to learn about developments in electrochemistry. He had been interested in the area for some time, and had worked with another privatdozent, Hans Luggin, who gave theoretical lectures in electrochemistry and physical chemistry. Haber's 1898 book "Grundriss der technischen Elektrochemie auf theoretischer Grundlage" (Outline of technical electrochemistry based on theoretical foundations) attracted considerable attention, particularly his work on the reduction of nitrobenzene. In the book's foreword, Haber expresses his gratitude to Luggin, who died on 5 December 1899. Haber collaborated with others in the area as well, including Georg Bredig, a student and later an assistant of Wilhelm Ostwald in Leipzig.