Boron: a Hunt for Superhard Polymorphs

Boron is a unique element, being the only element, all known polymorphs of which are superhard, and all of its crystal structures are distinct from any other element. The electron-deficient bonding in boron explains its remarkable sensitivity to even small concentrations of impurity atoms and allows boron to form peculiar chemical compounds with very different elements. These complications made the study of boron a great challenge, creating also a unique and instructive chapter in the history of science. Strange though it may sound, the discovery of boron in 1808 was ambiguous, with pure boron polymorphs established only starting from the 1950s-1970s, and only in 2007 was the stable phase at ambient conditions determined. The history of boron research from its discovery to the latest discoveries pertaining to the phase diagram of this element, the structure and stability of beta-boron, and establishment of a new high-pressure polymorph, gamma-boron, is reviewed

Scientific Rationality: Phlogiston as a Case Study

I argue that it was rational for chemists to eliminate phlogiston, but that it also would have been rational for them to retain it. I do so on the grounds that a number of prominent phlogiston theorists identified phlogiston with hydrogen in the late eighteenth century, and this identification became fairly well-entrenched by the early nineteenth century. In light of this identification, I critically evaluate Hasok Chang's argument that chemists should have retained phlogiston, and that doing so would have benefited science. I argue that these benefits would have been unlikely, and I go on to consider some more likely benefits and harms of retaining phlogiston. I conclude that there is a sense in which scientific rationality concerns what is permissible, as opposed to what is required, so that retention and elimination may, at least sometimes, both be rationally permissible options

Boron: a hunt for superhard polymorphs

Boron is a unique element, being the only element, all known polymorphs1 of which are superhard, and all of its crystal structures are distinct from any other element. The electron-deficient bonding in boron explains its remarkable sensitivity to even small amounts of impurity atoms and allows boron to form peculiar chemical compounds with very different elements. These complications made the study of boron a great challenge, creating also a unique and instructive chapter in the history of science. Strange though it may sound, the discovery of boron in 1808 was ambiguous, with pure boron polymorphs established only starting from the 1950s— 1970s, and only in 2007 was the stable phase at ambient conditions determined. The history of boron research from its discovery to the latest discoveries pertaining to the phase diagram of this element, the structure and stability of β-boron, and establishment of a new high-pressure polymorph, γ-boron, are reviewed

High-temperature electrochemistry of calcium

Electrolytically produced calcium is one of the most demanded materials in obtaining pure materials. At the same time, the existing technologies and devices for the electrolytic production of calcium were developed in the last century, and at present there are practically no works aimed at optimizing them. However, increasing the capacity and efficiency of existing devices for the production of calcium is in demand. To analyze possible ways to improve calcium production, a comprehensive understanding of the processes occurring at the electrodes and in the electrolyte during electrolytic production of calcium is required.This review briefly outlines the main points concerning the electrolytic production of calcium: from a brief history of the development of methods for the electrolytic production of calcium and established ideas about its physicochemical processes to information about new developments using the electrolysis of CaCl2-based melts. Review content: brief history of process development; base electrolyte for calcium production, including preparation of CaCl2 and influence of additions on it physicochemical properties; data on calcium solubility in CaCl2; information about alternative electrolytes for calcium production; short description of electrode processes in the CaCl2-based melts; proposed technologies and devices for the electrolytic production of calcium. keywords: calcium, calcium chloride, ion-electron liquid, Cu–Ca alloy, molten salt, calcium solubility, electrode processes, inert anode, electrolysis, current efficiency, electrolyzer DOI: https://doi.org/10.15826/elmattech.2022.1.00

Scientific Rationality: Phlogiston as a Case Study

I argue that it was rational for chemists to eliminate phlogiston, but that it also would have been rational for them to retain it. I do so on the grounds that a number of prominent phlogiston theorists identified phlogiston with hydrogen in the late eighteenth century, and this identification became fairly well-entrenched by the early nineteenth century. In light of this identification, I critically evaluate Hasok Chang's argument that chemists should have retained phlogiston, and that doing so would have benefited science. I argue that these benefits would have been unlikely, and I go on to consider some more likely benefits and harms of retaining phlogiston. I conclude that there is a sense in which scientific rationality concerns what is permissible, as opposed to what is required, so that retention and elimination may, at least sometimes, both be rationally permissible options

High-Temperature Electrochemistry of Calcium

Received: 12 July 2022. Accepted: 03 September 2022.Electrolytically produced calcium is one of the most demanded materials in obtaining pure materials. At the same time, the existing technologies and devices for the electrolytic production of calcium were developed in the last century, and at present there are practically no works aimed at optimizing them. However, increasing the capacity and efficiency of existing devices for the production of calcium is in demand. To analyze possible ways to improve calcium production, a comprehensive understanding of the processes occurring at the electrodes and in the electrolyte during electrolytic production of calcium is required. This review briefly outlines the main points concerning the electrolytic production of calcium: from a brief history of the development of methods for the electrolytic production of calcium and established ideas about its physicochemical processes to information about new developments using the electrolysis of CaCl2-based melts. Review content: brief history of process development; base electrolyte for calcium production, including preparation of CaCl2 and influence of additions on it physicochemical properties; data on calcium solubility in CaCl2; information about alternative electrolytes for calcium production; short description of electrode processes in the CaCl2-based melts; proposed technologies and devices for the electrolytic production of calcium

Tenth annual report of the Board of Regents of the Smithsonian Institution, showing the operations, expenditures, and condition of the institution, up to January 1, 1856. and the proceedings of the Board up to March 22, 1856.

835 S.misdoc.7334-1Annual Report of the Smithsonian Institution. [867] Research and publications relating to the American Indian.1856-9

Tenth annual report of the Board of Regents of the Smithsonian Institution, showing the operations, expenditures, and condition of the institution, up to January 1, 1856. and the proceedings of the Board up to March 22, 1856.

Annual Report of the Smithsonian Institution. [867] Research and publications relating to the American Indian