Letter, from Robert Hunt to Sir John Herschel, dated at Devonport Autograph letter signed by sender. Is grateful for the suggested emendations to his paper. Comments on the action of iodine on silver and its oxide. When can he expect publication of his paper? Has noted a peculiar property in the calorific rays when copying engravings. Encloses some Daguerreotype papers. 8 August 1840