Notes for students in chemistry : being a syllabus of chemistry compiled mainly from the manuals of Fownes-Watts, Miller, Wurz, and Schorlemmer / by Albert James Bernays.

  • Albert Bernays
Date:
1878
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Licence: Public Domain Mark

Credit: Notes for students in chemistry : being a syllabus of chemistry compiled mainly from the manuals of Fownes-Watts, Miller, Wurz, and Schorlemmer / by Albert James Bernays. Source: Wellcome Collection.

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    It is a constituent of most minerals, and of a great number of ortranic compounds. When bodies are burnt in oxygen, tliey oxydize, and increase in weight. Thus at a temperature of 315°, Mercury (Hydrar- gyrum llg) slowly oxydizes and becomes red in colour, and when further heated gives off oxygen again. Priestley in 1774 first prepared oxygen from mekcurio oxihe. Prep. i. From mercuric oxide HgO, by heat: 2HgO = 2Hg + 0,. 2. From manganese dioxide MnO„, by heat: manganous-manganic oxide MujO^ remains. 311062 = M1I3O4 -i- 0„. One kilogramme (2.2 lbs., each pound of 7000 grains) of the ore will yield about 50 litres of oxygen. 3. From barium dioxide BaO,, by heat; BARIUM OXIDE BaO remains. 2Ba02 = 2BaO + Oj. 4. From hydrogen oxide OH2 by electrolysis ; oxygen separates, because the electro-negative element, at the positive pole or platinode. 4. From potassium (kalium) chlorate KCIO3 by heat: potas- sn'M CHLOKiDE KCl remains. 2IVCIO3 = 2KCI + 3O2 (thechemi- cal action is more correctly : 1. 2C10„0K = CIK -f CIO3OK -j- O2. 2. CIO3OK = CIK + 2O2). [122.6 parts by weight of potassiiun chlorate will yield 48 parts by weight of oxygen. One hundred parts therefore : 122.6 : 100 :: 48 : x= 39.15.] Forother methods, see also hydrogen snLPHATE S02(OH)2; manganese dioxide Mn02; potassium dichromate CrjOjKj; and potassium chlorate Cld2(0K), p. 20. Ozone O2O = 2 vols. An allotropic modification of oxygen, or oxygen under difierent physical and ciiemical aspects. By Schoubein. Best prepared by Siemens' induction coil, in action, upon oxygen. Also by moist phosphorus upon air or oxygen. Gas of peculiar metallic odor, insoluble in water, in all;aline and acid solutions. Absorbed by solution of potassium iodide KI. Irritates respiratory organs. Instantly decomposed at 290° into oxygen gas ; two volumes into three. Is contained in minute c^uantities in pure air, but is instantly removed by putrescent matter. A grand oxydizing agent: bleaches also and disinfects. Iron, mercury, copper and iodine are oxydized by it, and so ia also silver leaf if ozone moist. Best test for ozone is a paper soaked in solution of potassium iodide and stnrch : the liberated iodine blues the paper. Thus: Ofi + 2KI + OHj = 2HOK + O2 + I2. ^ II. Hydrogen H = 1. = 2. A monad element: the standard of atomic weights. Color- less, tasteless and inodorous gas, at least when pure. Inlliiin- mable when hented in air or in oxygen, burning into Hydrogen oxide or water OU^. Tlio lightest of all gases. Its density as compared witii air 0.0691. One litre weighs only 0.0896 of a