172 MiscellniieoHS Intelligence . 



nature. It dissolves in caustic alkalies rather more slowly than 

 the yellow acid of tungsten, and loses its colour. The solution 

 yields the ordinary tungstates. If heated in an open cylindri- 

 cal vessel, it becomes yellow at the surface, but remains blue 

 within ; a proof that its change of colour is produced by the ac- 

 cess of air. When heated until the yellow colour was perfect, 

 it gained in weight, but the increase was never more than 

 0.0Q25, or at the very utmost 0.003 of its weight. 



I have found that tungsten forms an oxide beneath the acid. 

 It may be produced by passing hydrogen gas over red hottung- 

 stic acid in a tube. When the hydrogen passes without deposit- 

 ing vapour of water, the acid is reduced to the state of oxide. 

 This oxide is a chocolate-coloured powder which does not in 

 the moist way combine either with acids or bases. It takes 

 fire at a temperature much below redness, and burns like tin- 

 der : 100 parts of the oxide produce 107 of tungstic acid, from 

 whence it follows that the oxygen in this oxide is to that in the 

 acid as 2 to 3. 



On the much disputed and uncertain subject of the oxides of 

 antimony, M. Berzelius after remarking on the difficulty of 

 giving an accurate result, states that he has found two data 

 which are easy to verify and important in their evidence : the 

 one is, that 100 of antimony oxidated by nitric acid, and heated 

 red, and sufficiently to decompose all antimonic acid, gives 

 124.8 of antimonious acid. The second equally invariable 

 point is, that when antimonious acid is mixed with pure anti- 

 mony, pulverized and heated in close vessels without access of 

 air, the acid is converted into fusible oxide combining with a 

 portion of the mixed metal, equal to one-third of that in the 

 antimonious acid, proving that the ratio between the oxygen 

 in the oxide and that in the acid is as 3 : 4. The composition 

 is as follows : 



Oxide of Antimonyi^ ^ 



•' (^Oxygen 



Antimonious acid \r^ ^ 



/Oxygen 



... -1 C Antimony 



Antimonic acid <^ •' 



/Oxygen 



C1-1- (Silicum 



/Oxygen 



Deutoxide of Copper Iq^PP^J^ 



3. Oxide of Chromium. — If the hydrated green oxide of chro- 



