Chemistry and Physics. 521 



obtain it in a pure condition. He observed, however, the forma- 

 tion of a red compound under certain conditions, and found that 

 this compound could be prepared by the action of hydrogen 

 peroxide upon pure red mercuric oxide. This product has the 

 appearance of red phosphorus and has a composition correspond- 

 ing to the formula Hg0 2 . Its preparation is difficult, since 

 diluted hydrogen peroxide reduces it, and therefore it cannot be 

 washed, but the hydrogen peroxide can be removed by evapora- 

 tion in a desiccator at a low temperature. It is extremely unstable, 

 and even when covered with liquid it gives small local explosions 

 when stirred with a glass rod. The dry substance explodes 

 violently when slightly heated, or by concussion or friction. The 

 author considers the compound to be a mercuric derivative of 

 hydrogen peroxide, and upon theoretical grounds he supposes 

 that the film formed upon metallic mercury may be the corre- 

 sponding mercurous derivative, Hg o 2 . — Jour, prakt. Chem., lxx, 

 273. h. l. w. 



3. A Supposed New Element in Thorianite. — In connection 

 with the working up of 5 cwt. of thorianite from Ceylon belong- 

 ing to Sir William Ramsay, C. de B. Evans has observed some 

 colorations that could not be accounted for in the examination 

 of the tin group of metals. What was evidently a brown sul- 

 phide was eventually isolated with arsenious sulphide, which it 

 resembles in being insoluble in hydrochloric acid and readily 

 soluble in ammonium carbonate solution. Like arsenious sul- 

 phide it dissolves in nitric acid, but the concentrated syrupy 

 liquid has a strong golden-brown color, and leaves on evapora- 

 tion at 120° a brown hygroscopic oxide. This is reduced by 

 hydrogen at 250-300° to a black oxide, and then at a higher tem- 

 perature to a dark grey, non-volatile metal which melts at a 

 bright red heat. After many months of work only about - 05g. 

 of the brown oxide was collected from about one-third of the 

 mixed sulphides, and this was not free from arsenic. This cor- 

 responds to less than one gram per ton of thorianite. It is prob- 

 able that this small amount of substance would not have been 

 detected at all, had it not been for the fact that the sulphide 

 dissolves in water, Which is colored brown by a very small quan- 

 tity. This solubility greatly increases the difficulty of separa- 

 tion. Attempts to determine the equivalent of the metal indicate 

 a considerably higher equivalent than that of arsenic. A pre- 

 liminary spectroscopic examination revealed no new lines. Inci- 

 dentally in this investigation more knowledge was gained of the 

 composition of thorianite, and it can be stated positively that 

 this mineral contains arsenic, mercury, bismuth, molybdenum and 

 selenium. — .Tour. Chem. Soc, xciii, 666. h. l. w. 



4. Stereochemistry, by A. W. Stewart, 12mo, pp. 583. Lon- 

 don, 1907 (Longmans, Green & Company). — The author of this 

 book has not attempted to give a complete treatment of every 

 branch of the subject of stereochemistry, since it was found 

 impracticable to mention, in a book of reasonable size, all the 



