A treatise on chemistry. Vol. 1, The non-metallic elements / by Sir H.E. Roscoe & C. Schorlemmer ...

  • Roscoe, Henry E. (Henry Enfield), 1833-1915.
Date:
1881
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on chemistry. Vol. 1, The non-metallic elements / by Sir H.E. Roscoe & C. Schorlemmer ... Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

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    Sulpllur, S . . 25-48 - 31-98 = 0-796 Antimony, Sb . 17-76 -r 1220 = 0-146 ) Arsenic, As . 11-55 ^ 74-9 = 0-154 J Copper, Cu 30-73 4- 630 = 0-488\ Iron, Fe. 1-42^ 55-9 = 0-023 / Zinc, Zn 2-53-f- 64-9 = 0-339 r Silver, A<T O 10-53^ 107-66 = 0-099; 0-300 0-649 10000 If the several percentage weights be divided by the corre- sponding atomic weights, and if the resulting quotients of the isomorphous constituents be added together, the relation between these quotients will be found to correspond closely with the 5 : 2 :4, or the formula of the Fahl-ore is— 2[(Cu,Ag,Zn,re)2S] + (Sb,As)2 S3. Dimorphism and Trimoephism. 468 Even before Hatiy started the idea that bodies which possess an identical chemical composition crystallize in the same form, Vauquelin had noticed that titanic acid occurs as rutile and anatase, two minerals possessing distinct crystalline forms. In like manner, Klaproth pointed out that hexagonal calcspar is the same chemical compound as rhombic arragonite. These ex- ceptions to Haiiy's law were then explained by the presence in the compound, of some impurity which has the pov/er of altering the crystalline form. 11ms, arragonite was found to contain small quantities of strontium carbonate, a mineral which is found crystallized in the same form, and this smaU proportion was supposed to exert so powerful an action as to compel the calcium carbonate to assume a rhombic form. In 1821, Mitscherlich proved that this property of one and the same substance crystallizing in two distinct forms is common to many bodies both elementary and compound, and he termed such bodies Dimorpliom. Other substances, again, are capable of existing in three distinct crystalline forms. These Mitscherlich termed Trimoiyhous substances. If, lastly, two substances exhibit a double isomorph- ism, they are said to be Isodimorphous. The trioxides of