‎"LORENZ, L. - THE LORENZ-LORENTZ THEOREM.‎
‎Experimentale og teoretiske Undersøgelser over Legemernes Brydningsforhold. (Experimental and theoretical investigations on the refractions in matter).‎

‎Kjøbenhavn (Copenhagen), Bianco Luno,1869. 4to. Uncut and unopened in orig. printed wrappers. [Off-print from: Vidensk. Selsk. Skr., 5 Række, naturvidenskabelig og matematisk Afd., 8 Bd. V.]. Pp. (203-)248. A mint copy.‎

Reference : 41671

‎First printing, off-print in original printed wrappers of this groundbreaking paper.""A further remarkable result of Lorenz' optical researches on the basis of his fundamental wave equation was the well-known formula (Lorents-Lorenz formula) for the refraction constant R... His first paper on the refraction constant, in which he also gave an experimental verification of his formula in the case of water, dates from 1869. In 1870 H. A. Lorentz arrived at the same result, independently of Lorenz."" (D.S.B. VIII:501).‎