Volume 1
A treatise on chemistry / by H.E. Roscoe and C. Schorlemmer.
- Henry Enfield Roscoe
- Date:
- 1877-1892
Licence: Public Domain Mark
Credit: A treatise on chemistry / by H.E. Roscoe and C. Schorlemmer. Source: Wellcome Collection.
760/792 page 744
![Sulphur, S . 25-48 - 3F98 = 0-796 Antimony, Sb 17-7G - 1220 = 0-146 } 0-300 Arsenic, As 11-55 4- 74-9 = 0-154 j Copper, Cu 30-73 - 630 = 0-488 \ Iron, Fe. 142 -4- 55-9 = 0-023 ( O'fUQ Zinc, Zn 253- 64-9 = 0-339 ( yj uid Silver, A o' O 10-53- 107-66 = 0-099; 10000 If the several percentage weights he 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,Fe)2S] + (Sb,As)2 S3. Dimorphism and Trimorpiiism. 468 Even before Haiiy 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. I11 like manner, Klaproth pointed out that hexagonal calcspar is the same chemical compound as rhombic arragonite. These ex- ceptions to Hatty’s law were then explained by the presence in the compound, of some impurity which has the power of altering the crystalline form. Thus, arragonite was found to contain small quantities of strontium carbonate, a mineral which is found crystallized in the same form, and this small 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 Dimorphous. Other substances, again, are capable of existing in three, distinct crystalline forms. These Mitscherlich termed Trimorphous substances. If, lastly, two substances exhibit a double isomorph- ism, they are said to be Tsodimorphous. The trioxides of](https://iiif.wellcomecollection.org/image/b28122409_0001_0762.jp2/full/800%2C/0/default.jpg)
