388 Intelligence and Miscellaneous Articles. 



accordance with that of the yellow oxide : they fixed 50 as the quan- 

 tity of oxygen contained in 1G0 of the peroxide, stating at the 

 same time that when reduced to the protoxide by calcination it lost 

 33 per cent. As the protoxide contains about 10 per cent, of oxygen, 

 the 67 remaining parts would contain 67, which would give a total 

 of 39*7, differing 10 from their analysis. 



When the yellow oxide of bismuth is moderately heated with 

 potash, the mixture becomes brown, and after washing, a brownish 

 powder remains, which gives chlorine with muriatic acid. As, how- 

 ever, by this process but little of the peroxide is obtained, the fol- 

 lowing process is recommended instead of it by M. Stromeyer : 

 Heat the oxide obtained by calcining the subnitrate with a solution 

 of chloride of potash or soda, which is readily prepared by decom- 

 posing chloride of lime with the alkaline carbonates. When cold 

 but little action takes place, and even when heated the process goes 

 on but slowty, so that the ebullition must be continued for some 

 time. The oxide of bismuth assumes at first a fine ochre yellow 

 colour, and at length becomes deep brown. It is then to be well 

 washed, and in order to separate the protoxide which may remain, 

 it is to be treated with cold nitric acid, diluted with 9 parts of water ; 

 it is to be added in excess to prevent the formation of subnitrate of 

 bismuth. It is then to be washed, at first with weak acid, and then 

 with water, and to be dried by a gentle heat. 



The peroxide thus prepared is a heavy deep-brown powder, strongly 

 resembling peroxide of lead. When exposed to a temperature near 

 that of boiling mercury, it is decomposed, yellow oxide remaining 

 and oxygen gas being evolved. When mixed with powdered char- 

 coal, and heated, it burns vividly; the mixture may be fired by a 

 live coal, and it continues to burn like amadou : the residue is a 

 mixture of metal and protoxide. Hydrogen, at a moderate tem- 

 perature, reduces it to protoxide, and at a higher one to the state of 

 metal. When heated with sulphur it is quickly converted into 

 sulphuret: it forms no compounds with acids : muriatic acid evolves 

 chlorine, hydriodic acid converts it into a fine brown iodide, and 

 the liquor becomes yellow owing to free iodine. Cold sulphuric 

 acid expels oxygen, but if dilute, heat is requisite, and phosphoric 

 acid acts in the same way. Cold nitric acid, containing no nitrous 

 acid, acts but feebly upon it, but when heated it evolves oxygen. 

 The acetic, oxalic, tartaric, and citric acids, do not act upon it, 

 even when heated. The fixed alkalies and ammonia have no effect 

 upon this peroxide : its composition is readily determined by ascer- 

 taining the loss of weight it suffers by heat ; 12*12 parts lost 059 

 of oxygen, consequently 100 parts are composed of 95*141 prot- 

 oxide and 4859 oxygen. According to the experiment of Lajer- 

 hielm, the protoxide is composed of an atom of bismuth =71, and 

 an atom of oxygen = 8 ; in the 95*141 of protoxide there are then 

 85*507 metal + 9*634 oxygen, that is to say, nearly double the 

 quantity expelled by heat. The peroxide is thus composed of 

 2 atoms metal and 3 of oxygen. 



Neither the subnitrate nor the hydrate answers so well for prepar- 



