In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

An approximation of it named for Russell uses the TDS value to determine one of its parameters via the Langelier approximation, while one constant that appears in it has units of moles per kilogram to the one half power, according the Bates-Guggenheim convention. Along with Guggenheim, Scatchard and Bronsted improved upon this model by developing the SIT theory, and that model has a better fit than a modification of it named for Davies. This relationship assumes the existence of only long-range interactions, and it was extended to account for Brownian motion by Lars Onsager. It assumes that the solvent is structure-less and that the solution is dilute, and the theory behind it implies that the electrostatic potential falls off exponentially when r is greater than the atomic radius due to screening by counter ions. For 10 points, identify this equation which is used to calculate the activity coefficients, and is named for a German and a Dutch scientist. 
Science

This artist depicted a certain structure "at Bellevue" and "at Montbriand". In addition to those depictions of The Pigeon House, he depicted the titular shirtless black man in jeans resting his head in one work, while a man dressed completely dressed in white gestures to a black and white harlequin in another. In addition to The Negro Scipion and Fastnacht, he created various depictions of an Avenue at (*) Chantilly, and Paul Alexis reads to one of his friends in another work. Rilke wrote some letters on this artist, who depicted a large crevice in the title structure in his House with Burst Walls, and depicted his mother knitting as his sister plays the piano in The Overture to Tannhuser. For 10 points, name this artist who was represented by Claude Lantier in The Masterpiece by Emile Zola.
Fine Arts

The title character of this novel is addressed as Colonel throughout the book, and feels guilt for an event that took place during the Civil War but threatens to ruin him by the end of the novel. The novel begins with an interview by one of the author's recurring characters, the journalist Bartley Hubbard, who writes a piece about a self-made millionaire from Vermont who deals in paint. When he finds out that a local Bostonian dilettante, Tom Corey, has fallen in love with one of his daughters he decides to build a new house on Beacon Hill. FTP identify this 1885 novel about a man who loses all his wealth but regains his soul, written by William Dean Howells.

Literature