M. Hautefeuille on the Artificial Production of Rutile, tyc. 537 



times its weight of distilled water, and several large rods of pure 

 zinc placed in the cold nitrate. Within eight to twelve hours all 

 the thallium in the solution was precipitated in the form of a 

 black porous heavy powder, mixed with some hydrated oxide of 

 zinc, from which it could be readily separated by elutriation. 

 This thallium was dissolved in dilute sulphuric acid with the 

 addition of a few drops of nitric acid^ evaporated to dryness, re- 

 dissolved in water, and the thallium again precipitated by the 

 addition of some pieces of distilled zinc. The thallium is sepa- 

 rated out to the last trace, often in the form of beautiful metallic 

 lustrous needles. 



Bottger* investigated a saline mixture obtained in cold 

 weather from the mother-liquors from which common salt has 

 been extracted at the Nauheim Salt Works. It is a very deli- 

 quescent substance, and is in considerable use by the confec- 

 tioners for freezing-mixtures. It was found to consist of the 

 chlorides of magnesium, potassium, and sodium, besides compa- 

 ratively large quantities of the chlorides of ccesium and rubidium, 

 with traces of chloride of thallium. Bofctger states that the Nau- 

 heim mother-liquor is at present the readiest source of ccesium and 

 rubidium. According to his observations, thallium almost inva- 

 riably accompanies potassium, caesium, and rubidium — from which 

 fact, and from its other properties, spite of its being precipitated 

 by sulphuretted hydrogen, an indication is given that this metal 

 must be classed with the alkalies. 



Hautefeuille describes the artificial preparation of Rutile, Brook- 

 ite, and their varieties f. 



Rutile is obtained by heating in a current of hydrochloric acid 

 a mixture of titanate of potash and chloride of potassium. The 

 mixture is placed in a platinum crucible enclosed in an earthen 

 one, in the lid of which are luted two porcelain tubes through 

 which the current of gas passes. The crystals have the same 

 form as those obtained by M. DevilleJ, by passing hydrochloric 

 acid over amorphous titanic acid heated to redness. The density 

 of the crystals obtained by M. Hautefeuille is 4*3, the same as 

 that of natural rutile. 



Acicular Rutile. — By heating a mixture of titanate and fluo- 

 titanate of potassium to bright redness in a current of hydro- 

 chloric acid, prismatic crystals are obtained terminated by octa- 

 hedra. In their shape and colour, which is a golden yellow, they 

 resemble the acicular rutile enclosed in the quartz of Madagascar. 



* Liebig's Annalen, September 1863. 

 f Comptes Rendus, July 20, 1863. 

 X Phil. Mag. vol. xxii. p. 516. 

 Phil. Mag. S. 4 No. 178. Suppl Vol. 26. ' 2 N 



