In 1885, the art critic John Ruskin and physicist Oliver Lodge exchanged a remarkable series of letters debating why the sky is blue and whether industrial pollution was changing Britain's atmosphere.Here, Anna Marie Roos presents the first complete critical edition of the 1885-86 correspondence between John Ruskin and physicist Oliver Lodge, recovering a remarkable exchange that has been misrepresented for over a century. The correspondence began when Lodge sent Ruskin his 1884 British Association lecture 'Dust', which criticised Ruskin's account of cloud formation in Modern Painters. What followed was not, as Lodge's subsequent publications implied, a case of a patient scientist instructing an artistically gifted but scientifically naïve empiricist. It was a genuine collaborative investigation in which both men brought distinct but equally consequential forms of expertise to questions of atmospheric physics.Drawing on the complete archival correspondence held at the Cadbury Research Library, University of Birmingham, this work demonstrates that Ruskin's decades of systematic cloud observation and his Alpine use of the cyanometer gave him contributory expertise. His challenge to the dust hypothesis for the blueness of the sky was ultimately vindicated by Lord Rayleigh's proof that molecular scattering, not suspended particles, explains the colour of pristine upper atmosphere.The introduction contextualises the exchange within Victorian debates about disciplinary boundaries between mathematical physics and aesthetic empiricism. Roos argues Lodge's editorial suppressions was strategic boundary-work that served his professional ambitions. A technical appendix connects the central scientific debates — Rayleigh versus Lorenz-Mie scattering, Stokes's Law, and kinetic theory — to contemporary climate science.