The natural combination of sulfates of bivalent metals with monovalent metal sulfates in a 1:1 ratio results in the formation of double sulfates chemically distinct from their original constituent species. By the 1850s, a number of double sulfates had been artificially synthesized, including ammonium iron(II) sulfate or "Mohr's salt" by Karl Friedrich Mohr. Some chemists, including one Vohl, subsequently claimed to have isolated numerous double-double and multiple-double sulfates including supposed "triple-double," and "quadruple-double" structures. These were purportedly the result of two double sulfates of Type I (differing in the bivalent metal Mb) combining in definite integral proportions to yield new molecular double salts. Others who had attempted to reproduce those experiments reported their inability to do so. Prior to Ray's taking up the problem, in 1886, Percival Spencer Umfreville Pickering and Emily Aston had concluded in their paper that double-double and higher-order sulfate salts did not exist as definite structures, deeming Vohl's experimental findings inexplicable. While Ray noted such findings placed Vohl's research in doubt, he reasoned "the position was unclear and further research was called for." Ray was awarded the Hope Prize which allowed him to work on his research for a further period of one year after completion of his doctorate. His thesis title was "Conjugated Sulphates of the Copper-magnesium Group: A Study of Isomorphous Mixtures and Molecular Combinations". While a student he was elected vice-president of the University of Edinburgh Chemical Society in 1888. Career Scientific research Mercurous nitrite Around 1895 Prafulla Chandra started his work in the field of discovering nitrite chemistry which turned out to be extremely effective. In 1896, he published a paper on preparation of a new stable chemical compound: mercurous nitrite. This work made way for a large number of investigative papers on nitrites and hyponitrites of different metals, and on nitrites of ammonia and organic amines. He and his students had crumbled this field for several years, leading to a long discipline of research laboratories. Prafulla Chandra said that it was a new chapter in life that started with the unanticipated discovery of mercurous nitrite (NOT mercurous nitrate). Prafulla Chandra, in 1896, noticed the formation of a yellow crystalline solid with the reaction of excess mercury and dilute nitric acid. Unfortunately multiple sources wrongly attribute this as mercurous nitrate instead of mercurous nitrite. The ionic reactions involved are 2Hg0 → Hg22+ + 2e− (Net reaction in presence of excess mercury) NO3−