Autograph Letter Signed, to Thomas Twining, about forthcoming lectures at the Society of Arts, suggesting that Letheby talks on the relative values of food, and the treatment of food in the the processes of preservation and cooking, also on the adulterations of food. 4 pp. 7 x 4½ inches, fine. 17 Sussex Place, Regents Park, 30 November 1867. Henry Letheby (1816 –1876), analytical chemist and public health officer. He was lecturer on chemistry at the London Hospital, and for some years medical officer of health and analyst of foods for the City of London. He was also appointed chief examiner of gas for the metropolis under the Board of Trade. Letheby was an exceedingly accurate technological chemist, and contributed many papers to The Lancet and other scientific periodicals. Letheby’s chief work was a treatise on Food, its Varieties, Chemical Composition, &c. .