202 ANNUAL OF SCIENTIFIC DISCOVERY. 



ordinary temperature, a solution of bichloride of platinum is 

 immediately decomposed, the platinum being- thrown down as the 

 finest platinum-black. Chloride of gold deposits metallic gold in 

 a similar manner, and even zinc may be thus obtained from a 

 solution of its chloride. Dingler's Polytech. Jour. 



Sodium as a Flux for Minerals. Dr. ScJionn. A steel cruci- 

 ble l inches deep, and the same in diameter, is heated over a 

 lamp ; into this are projected a few pieces of metallic sodium, 

 and afterwards the finely divided and dry mineral is added. The 

 crucible is then covered and heated red-hot. As soon as the reac- 

 tion is finished, the contents of the crucible are allowed to cool, 

 and water is cautiously added sufficient for the purposes of filtra- 

 tion. The fused mass is then thrown upon a filter and thoroughly 

 washed. In the filtrate will be found the electro-negative con- 

 stituents of the mineral, combined with the sodium, such as sul- 

 phur, cyanogen, chlorine, chromic acid, silica, molybdic and 

 tnngstic acids, and such oxides as are soluble in soda-lye. On the 

 filter will be found the metals and their oxides, also the lower 

 oxides of titanium, molybdenum, tungsten, and possibly silica 

 and alumina. The contents of the filter and the filtrate can be 

 treated according to the order of analysis. Chemical News. 



Action of Sulphur on Gold. William Skey, of the Geological 

 Survey of New Zealand, having investigated the reported loss of 



fold during the process of extraction at the Thames gold-fields, 

 nds that numerous samples of bright, clean-looking gold, of all 

 degrees of fineness, refuse to amalgamate on any part of their 

 natural surfaces, and that in such cases sulphur is always present. 

 He finds, also, that gold exposed to a moist atmosphere of -sul- 

 phuretted hydrogen, or to sulphide of ammonium, absorbs sulphur 

 without change in appearance, and that after such treatment it 

 refuses to amalgamate. The gold may be restored to its original 

 condition by the action of chromic or nitric acids, and by roasting 

 in the air. A large portion of the surface of the gold being thus 

 naturally sulphurized, the author considers the loss as resulting 

 from the failure to amalgamate of those particles which escape 

 abrasion in the milling process. Chemical News. 



Influence of Ozone on the Explosibility of Picrate of Potassium. 

 M. Houzseau, whose researches on ozone are well known, has 

 made some experiments on the action of this substance on picrates. 

 He prepared a flask of ozone, into which he introduced 5 decigrams 

 of picrate of potassium ; an explosion immediately ensued, shat- 

 tering the vessel to fragments by its violence. He then operated 

 with a mixture of air and ozone (in which the ozonometer 

 marked 500 millimeters), and, on adding the picrate, the explo- 

 sion again occurred with the same intensity. Proceeding by 

 degrees he arrived at the conclusion that picrate of potassium is 

 decomposed when the ozonometer marks 45 millimeters. Drug- 

 gists' 1 Circular. 



Action of Ozone on Explosive Bodies. According to the experi- 

 ments of M. Jouglet, nitro-glycerine will explode in a vessel 

 containing ozone ; the same is true of dynamite, iodide of nitrogen, 



