Chemistry and Physios. 73 



Fe, Co, and Ni and the' metals of the platinum group fall in 

 the same series in Mendelejeff's periodic system of the ele- 

 ments, which gives additional grounds for putting this mineral 

 in the pyrite group. 



The hardness of the mineral is between 6 and 7, which was 

 determined by placing selected crystals on a bright feldspar 

 surface, pressing down on them with a soft pine stick and rub- 

 bing back and forth ; the sperrylite repeatedly cut into the feld- 

 spar but could not be made to scratch quartz. The crystals 

 have no distinct cleavage but are very brittle and break with 

 an irregular, probably conchoidal fracture. 

 . Mineral ogical Laboratory, Sheffield Scientific School, Dec. 12th, 1888. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. On the Vapor-density of the Chlorides of Indium, Gal- 

 lium, Iron and Chromium • and on two neio Chlorides of In- 

 dium. — Nilson and Pettersson have determined the vapor 

 density of the chlorides of indium, gallium, iron and chromium 

 by "V". Meyer's method, employing for the purpose vessels made 

 either of hard Thuringen glass or of porcelain. In the course of 

 their researches upon the indium chlorides they discovered two 

 new ones ; the mono-chloride, having a vapor density of 5*402 at 

 1300°-1400° and the formula InCl ; and the dichloride InCl 2 

 whose vapor density was found to be 6*885 at 1100°. The third 

 chloride carefully purified gave a vapor density of 8*156 at 606° ; 

 of 7-391 at 850°; of 6*716 at 1048 ; and of 6-234 at 1100°-1200°. 

 The formula InCl 3 gives 7*548 ; and hence the authors consider 

 this formula correct. The higher chloride of gallium gave the 

 vapor density 8*846 at 350° ; 6*118 at 440° ; 6*144 at 606°, and 

 5*185 at 1000°-1100° ; corresponding to the formula GaCl 3 which 

 requires 6*081. The lower chloride gave a density of 4*823 at 

 1000°-1100° and 3*568 at 1300°-1400° ; the formula GaCl a requir- 

 ing 4*859. Ferrous chloride at 1300°-1400° gave a vapor density 

 of 4*340; and at 1400°-1500°, one of 4*292; the formula FeCl 4 

 requiring 4*375. The higher chloride of chromium gave values 

 varying from 6*135 at 1065° to 4*580 at 1350°-1400°, the formula 

 CrCl 3 requiring 5*478. • The lower chloride gave a vapor density 

 of 7*800 at 1300°-1400°; 7*278"at 1400 o -1500°, and 6*224 at 1500° 

 -1600°. At a higher temperature the authors believe it would 

 reach 4*256 the value required by the formula CrCl 2 . — J. Chem. 

 Soc, liii, 814, October, 1888. G. p. b. 



2. On the Vapor-density of Ferric chloride. — Friedee and 

 Crafts have determined the vapor density of ferric chloride by 

 the method of Dumas taking the same precautions as with alumi- 



