Robert Kennedy DUNCAN (1868-1914), American chemist of Canadian origin, professor at Washington & Jefferson College in Washington; in 1901, he went to Paris to study radioactivity with Pierre and Marie Curie. 3 typed letters signed to Henri Becquerel. 2 pp. in-8 and 2 pp. in-4, Chemical Laboratory letterheads. Washington, Sept. 1901 - April 1902. In English and French. He has received his two publications and proposes to review them, but will wait for his agreement. "I am now writing to ask you to give me your distinguished advice on a research project that I have been considering. The study of radioactivity has led me to consider the physical basis of the sense of smell. On this subject, I have read Professor Tyndall's research in which he proves the power of absorption that odoriferous emanations have on radiant heat. I also came across an article by Mr Will. Ramsay in the English "Nature" of 22 June 1882, page 188, in which he suggests that it should be possible to obtain a spectrum resulting from the absorption of heat by odoriferous emanations (heat absorption spectrum). The whole article seems to me to be full of possibilities. Would you be so kind as to tell me whether this idea has been worked on [...]". In a third letter, he sent him a proof of his article on radioactivity and asked for his opinion. "The article will be published in the August number of Harper's Magazine. The subject proved too abstruse for McClure's constituency, but it was gladly accepted by Harper's as a fitting sequel to Prof. J.J. Thomson's article on Cathode Rays [...]".