192 Q,uarterly Abstract of European Chemistry. 



Chlorazotic Acid, by M. Baudrimont, (Journ. de Pharm. et de Chim. 

 Jan. 1844.) — The property that aqua regia has of dissolving gold and 

 platinum, and which has been supposed to be due to the presence of 

 chlorine, is shown to be owing to a peculiar acid, having for its com- 

 position Az O^Ch^. It can be obtained by mixing together two parts 

 of nitric and three parts of hydrochloric acids of commerce, when it 

 escapes in the form of red fumes, mixed at first with the vapor of a 

 little hydrochloric acid ; it can be condensed in a U tube placed in salt 

 and ice, and then appears as a liquid of a deep red color ; in this state 

 it attacks all metals when brought in contact with them ; with finely 

 divided silver it explodes immediately. In acting on metals it forms a 

 chloride and a nitrate. Its action on metallic oxides indicates that it is 

 an acid of a definite character, being represented by nitric acid, with 

 two atoms of oxygen substituted by two atoms of chlorine. 



Tlie Oxides of Gold, Purple of Cassius, and Fuhninating Gold, by 

 L. FiGXJiER, (Compt. Rend. April, 1844.) — The green powder described 

 by chemists as the protoxide of gold is found to be a mixture of me- 

 tallic gold with the oxide. This latter, instead of having the extreme 

 instability ordinarily allotted to it, is found to be the most unalterable 

 of all the oxides of this metal. It is a violet powder so dark as to ap- 

 pear black when in a hydrated state. It is an indifferent compound, 

 combining with both bases and acids. The hydracids produce a deposit 

 of gold, dissolving a tritoxide that is formed. With ammonia it forms 

 a violet fulminating compound ; at 250° C. (482° Fah.) it is decomposed. 

 The protoxide can be procured in various ways by treating the neutral 

 trichloride of gold with the protonitrate of mercury ; by acting upon 

 the tritoxide of gold with acetic or almost any of the organic acids, or 

 with the salts of their acids, vegetable or animal matter produces the 

 same effect. Figuier thinks that he has discovered a compound of 

 gold and oxygen containing more oxygen than any of its oxides previ- 

 ously known — it is called perauric acid. Its composition has not yet 

 been made out ; it is formed under the following circumstances : when 

 the tritoxide of gold is boiled with caustic potash, there is formed an 

 abundant precipitate of the protoxide of gold, without any escape of 

 oxygen, which must therefore combine with a portion of the tritoxide, 

 forming a compound more highly oxygenated, that remains dissolved in 

 the potash. The purple of Cassius when pure is shown to be a neutral 

 stannate of the protoxide of gold ; without regard to the manner in 

 which it may be formed, its formula is 3(St02) Au^ 0-|-4H0. The 

 stannic acid has been shown by Fremy to require three equivalents for 

 the formation of the neutral stannates. There is also a bistannate of 

 the protoxide, 6(St02) Au 0-|-4H0. The fulminating gold is sup- 



