UEBER DIE IDENTITAT DER SCHWINGUNGEN DES LICHTS MIT DEN ELEKTRISCHEN STROMEN. In Annales Der Physik Und Chemie, Vol 131, 1867, Pp. 243-263

Leipzig: Johann Ambrosius Barth, 1867. Quarter Leather. Very Good+. Octavo. Offered is entire Vol. 131 of Annalen der Physik und Chemie in nice quarter brown leather binding and marbled paper covered boards with raised bands spine, gilt letter spine. Ex-library with library bookplate front paste-down, small ink stamp front paste-down and copyright page, no other library markings. Very good+ copy with mild cover edge wear, small dampstain corner of half title and title page, not affecting article. First German edition (which originally appeared in 1867 in Danish in "Oversight over det Kongelige Danske Viidenskabernes Selskabs Forhandlinger") of Lorenz paper, which contains his important studies on the electomagnetic theory of light. "Most impressive of all Lorenz' achievement in optics is his electromagnetic theory of light, developed in a relatively unknown paper of 1867, two years after Maxwell's famous paper on the same subject. At that time Lorenz did not know Maxwell's theory, and his own approach was quite different. Lorenz's electromagnetic theory of light can be described briefly as an interpretation of the light vector as the currrent density vector in a medium obeying Ohm's law. This paper contains the fundamental equations for the vector potential and the scalar potential - for the first time - the corresponding retarded potentials expressed in terms of the current density vector and the electrical charge density. The concept of retarded potentials had already been been introduced in an earlier paper by Lorenz in connection with research on the theory of elasticity. He found that the differential equation for the current density vector was the same as his fundmental wave equation of the light vector, completed with a term which explains the absorption of light in conducting media, and that his theory led to the correct value for the velocity of light" - (DSB, VIII, pp. 501-502).