The article discusses sociologist Pierre Frederic Guillaume Leplay's contribution to sociology. In 1832, Leplay contributed an important paper to the Annales under the title of "Observations on the commercial movement of the chief mineral products between France and foreign countries for the last twelve years, and more especially for the years 1889, 1830 and 1881." The tables appended were compiled from the official returns of the customs. This valuable piece of statistical work attracted great attention, and largely responsible for passing of a measure in 1833. When this Commission was appointed Leplay was in Spain, whither he had been sent or an important mission. The re-opening of the lead mines of the filers do H Gador said the Sierra do Lugar had attracted the attention of all mining experts in Spain. The great work, however, was destined never to be written. The first period of Leplay's life, in which metallurgy ranked before social science in his interests, was drawing to a close. Henceforth he was to be occupied chiefly with administrative duties and the study of social problems. In 1851 he was a member of one of the juries at the Cheat Exhibition of 1861, and furnished to the French Government a report on cutlery and steel tools.