Chemistry and Physics. 57 



for a large number of those composed of liquid carbon dioxide. 

 Curiously enough this point was found to vary considerably : In 

 topaz, in three specimens, the critical point wasVxV , 2GT.° to 2S°, 

 and-.'7-.V toL'7-(i C. ; in two specimens of tourmaline, from America, 

 it was 27-27° and 26-9°; in five quartz specimens, it was 30-95°, 

 30-95°, 32-5°, 33-7° and 29°; in a beryl from Lurat, it was .jo'..2°; 

 in three oriental sapphires, 30-5° to 31°, 25-5° to 20°, and 29-5°. 

 The author explains this lowering of the critical point bv the tact 

 observed by Andrews that this effect is produced by the' presence 

 of an incondensable gas, perhaps nitrogen. The raising of the 

 critical point appears to him to be due to hydrochloric acid gas. 

 The facts observed seem to the author to have a bearing on 'the 

 question of the formation of some of these minerals, and he sug- 

 gests that corundum may have been formed by the action of 

 aluminum chloride or fluoride upon calcium carbonate, producing 

 alumina and carbon dioxide; the latter being condensed, would 

 form cavities in the alumina crvstals and would liquefy on cooling. 

 If the reaction were dry, the cavity would contain only the diox- 

 ide: but if moisture were present, it would contain water also. 

 With reference to the diamond, he suggests that it may have 

 been formed by the action of reducing agents upon very highly 

 compressed carbon dioxide at temperatures above its critical point. 

 — J. Chem. Soc, xxx, 237, Sept., 1876. a. f. b. 



4. On the Spectra of Indium.— Clayden and Heycock while 

 observing the spark spectra of the metals, in the Cavendish Lab- 

 oratory, Cambridge, noticed that instead of the three lines which 

 are ordinarily supposed to constitute the spectrum of indium, the 

 spark spectrum Veallv contained sixteen. The wave-lengths of 

 the three lines are given by Thalen as 45:*2. 4oo:i and 4 lei tenth- 

 meters. The second and third only of these lines are visible in 

 the spark-spectrum. The wave-lengths of the sixteen lines the 

 authors give as follows: 6906, 6193, 6114, 6095, 5922, 5905, 5862, 

 5820,5722,50 44. 5250. 40-0, 4050. 4G:i\ 4510, and 4K 1 tenth- 

 meters. The first of these lines is remarkable for its low refrangi- 

 bility, only potassium, strontium and antimony giving lower ones. 

 The wavelengths were not measured directly apparently, but 

 obtained bv interpolation from th seal of tin our-prism s| etro- 

 - p wit I "v hi h the measurements were made. —Phil. May., V, 

 ii. 387, Nov., 1876. «• F - B - 



5. On the Preparation of Hydroquinone.— Wkselskt and 

 Schuler have discovered a new and comparatively simple 

 method of | mm phenol of the ortho or 1 :2 

 series, hydroquinone. If nitrous acid vapors be conducted into 

 a cooled etherial solution of phenol, the mass is filled in a short 



- oived in 

 , ' 1 on, .f acid and two of water) mixed with 

 ; 1 ether added, becomes sulphate which by pr 



non-volatile mononitrophenol of fusing point 110°. If now an 



