Gas carbon

{{short description|Carbon}}

Gas carbon, or retort carbon, is a form of carbon that is obtained when the destructive distillation of coal is done or when coal gas or petroleum products are heated at high temperatures in a closed container.{{cite book|title=The Chambers Dictionary |edition=13th }}{{cite web |website=Merriam-Webster mobile search |title=gas carbon |access-date=5 December 2015 |url=http://i.word.com/idictionary/gas%20carbon}}{{cite web |website=atomistry.com |title=retort carbon |url=http://carbon.atomistry.com/retort_carbon.html}}{{cite book |last1=Eliot |first1=Charles William |last2=Humphreys Storer |first2=Frank |title=A Manual of Inorganic Chemistry Arranged to Facilitate the Experimental Demonstration of the Facts and Principles of the Science |date=1869 |pages=292-293}}{{cite book |last1=Houston |first1=Edwin James |title=The Elements of Chemistry For the Use of Schools, Academies, and Colleges |date=1883 |page=153}} It appears as a compact, amorphous, gray, crystalline solid left by chemical vapour deposition on the walls of a container or retort. It is a good conductor of heat and electricity, similar to graphite. Unlike graphite, it does not leave marks on paper.{{cite book |last1=Graham Graham |first1=Thomas |title=Elements of Chemistry Including the Applications of the Science in the Arts - Part 3 |date=1839 |page=300}}

Applications have included battery plates, and in arc lamps. It was also used in early microphones.{{Cite Q|Q133567763}}

Houston in 1883 described its use in arc lighting:

{{Blockquote|For the manufacture of the carbon electrode, the gas carbon is finely pulverized, washed, and mixed with lamp-black or other pure, finely divided carbon, and made into a paste with syrup, tar, or other carbonizable liquid. It is then forced through an opening in a strong cylinder by hydraulic pressure, and baked at a red heat for several hours, while surrounded by sand or similar material to exclude the air. The carbons are then allowed to cool, and are removed, and again soaked and burned, in order to increase their density and electrical conducting power.}}

while Atkinson noted in 1898:{{cite book |last1=Butterfield |first1=William John Atkinson |title=Gas Manufacture The Chemistry Of. A Practical Handbook on the Production, Purification and Testing of Illuminating Gas, and the Assay of the Bye-products of Gas Manufacture |date=1898 |page=319}}

{{Blockquote|For [electric arc carbon] especially, large pieces are in demand, and command a better price... It is, generally speaking, too valuable for use as fuel.}}

It has a specific gravity of around 2.35 to 2.4.