Chemistry and Physics. 241 



carbon and Loew to fluorine from dissociated cerium fluoride. 

 Becquerel and Moissax have examined the fluorite of Quincie 

 near Yillefranche, which is markedly odorous; and they find that 

 a gas is contained within this mineral, which can "be seen to 

 escape on breaking it under the microscope. On trituration this 

 substance evolves ozone, sets chlorine free from chlorides, pro- 

 duces silicon fluoride on heating with silicon and o-ives hvdrooen 

 fluoride with water. All these results seem to indicate that the 

 gas enclosed in this variety of fluorite contains a small quantity 

 of free fluorine. — C. B., cxi, 669; Ber. Berl. Ghem. Ges., xxiv, 

 (Ref.) 4, January, 1891. a. f. b. 



4. On the Chemical condition of Iodine in its Solutions. — 

 Gautier and Charpy have observed a remarkable relation be- 

 tween the color of iodine solutions and the character of the iodides 

 formed by the iodine which they contain. Thus solutions in 

 alcohol, ether, acetone, etc., are reddish-brown in color, while 

 solutions in carbon disulphide and chloroform are violet. If mer- 

 cury containing dissolved lead be agitated with the brown solu- 

 tion, a yellow precipitate of lead iodide is produced so long as 

 lead remains in the mercury or iodine in the solution ; minute 

 traces of lead only being required to show it. If, however, the 

 experiment be repeated with the violet solution a green precipi- 

 tate of mercurous iodide results; aud this equally whether the 

 mercury be pure or whether it contains so much lead as to be 

 pasty. With solutions having colors lying between these ex- 

 tremes, precipitates are obtained passing from yellow to green in 

 the same proportion as the solution passes from brown to violet. 

 A closer investigation seems to show that the iodine in the violet 

 solutions combines directly with mercury to form the green 

 iodide, even in presence of an excess of iodine; while the brown 

 solutions give mercuric iodide which dissolves in the solvent 

 (Hgl 2 being soluble to the extent of 0-00842 parts in alcohol and 

 only 0*00280 in carbon disulphide at 15°), and which facilitates 

 the formation of the lead iodide; mercurous iodide not appearing 

 until no more free iodine exists in the solution. The authors 

 attribute this dissimilar behavior of iodine solutions to the sup- 

 posed fact that the violet solutions contain iodine molecules of 

 simpler constitution than do the brown solutions ; a relation 

 evidently existing between the color of the solutions and their 

 molecular constitution. — C. B., cxi, 645; Ber. Berl. Ghem. Ges., 

 xxiii, Ref. 75 7, January, 1891. g. e. b. 



5. On the Properties of Carbon produced from Cyanogen. — 

 P. and L. Schetzexberger have examined the carbon which is 

 obtained on passing cyanogen gas through a porcelain tube heated 

 to a temperature near softening. It formed a dense polished 

 layer on the walls of the tube, resembling graphite. On putting 

 into the tube a boat of retort carbon covered with cryolite, how- 

 ever, the decomposition takes place at a cherry-red heat ; the tube 

 becoming gradually filled with a blackish-green deposited carbon 

 (A) consisting of a fibrous elastic mass, the fibers being felted 



