Intelligence and Miscellaneous Articles. 151 



iD 



the symbol Na PR When heated to redness, it gives at first a 

 quantity of water, then acid, and becomes black : the soda which 

 it contains may then be separated by water. The black powder 

 which remains appears to be a mixture of platina and oxide of pla- 

 tina, for it inflames a current of hydrogen passed over it, and gives, 

 with muriatic acid, muriate of platina, and a black powder, insoluble 

 in it, which becomes red in a detonating mixture of gases, and of a 

 grayish white colour. With oxalic acid this substance acts as a 

 mixture of oxide and of metal. 



Acetic acid separates from the salt in question all the soda which 

 it contains, and leaves oxide of platina, of an ochre yellow colour, 

 A small portion of this oxide dissolves in the acid, without impart- 

 ing any colour to it ; from which it appears that oxide of platina 

 dissolves with difficulty, or scarcely at all in acetic acid. It may 

 be objected to this observation that muriate of platina is not pre- 

 cipitated by acetate of soda, and that the mixture of these salts in 

 solution suffers no alteration, either by heat or solar light; but al- 

 cohol reduces the oxide which it contains to the spongy state, which 

 does not happen unless it is combined with acetic acid, for the mu- 

 riate is never reduced so quickly and so perfectly by alcohol. 



Formic acid decomposes platinate of soda completely at a gentle 

 heat, that is to say, all the oxide of platina is reduced, and a rapid 

 disengagement of carbonic acid gas takes place. Eight grains of 

 the salt, dried at 212°, gave with this acid five cubic inches of car- 

 bonic acid gas, consequently 105 grains of oxygen are combined 

 with platina in eight grains of the salt. 



The metal, reduced to the state of spongy platina, becomes 

 instantly red hot when put upon printing paper slightly impregnated 

 with alcohol. 



Oxalic acid dissolves platinate of soda when heated, with the de- 

 velopment of carbonic acid. A dark-coloured liquid is obtained, 

 which, on cooling, at first becomes green, and afterwards of a deep 

 magnificent blue colour : there are soon formed in it small needle- 

 shaped crystals, of a deep copper red colour, and a metallic lustre, 

 which are protacetate of platina Ft O. These crystals, when heated, 

 detonate : water separates, and carbonic acid is produced. The solu- 

 tion separated from the crystals is of a pale blue colour -, diluted 

 with water it becomes yellow, and by evaporation it becomes of a 

 deep blue colour. 



Dilute nitric acid readily dissolves platinate of soda ; the solution 

 is of a deep yellow colour. In a solution of nitrate of silver it gives 

 a yellow precipitate, which is totally dissolved by nitric acid if the 

 salt is free from chlorine j it is probably a nitroplatinate of silver. 



If muriate of platina be mixed with a little cream of lime, then 

 with a large quantity of lime water, and the filtered solution be ex- 

 posed to the sun, it quickly becomes as turbid as milk, and after 

 some hours it forms a flaky precipitate, which, after being boiled, is 

 a yellowish white powder. According to Herschel *, this product is 



* Sir John F. W. HerschePs observations on this substance will be 

 found in Lond. and Edinb. Phil. Mag , vol. i. p. 59. — Edit. 



