Intelligence and Miscellaneous Articles. 73 



DIFFERENCE BETWEEN ACETIC AND FORMIC ACIDS. 



M. Dobereiner distinguishes formic from acetic acid, by the pro- 

 perty which the former possesses of reducing the oxides of the noble 

 metals in the humid way, the formic becoming carbonic acid. If, for 

 example, acetic acid be added to a saturated solution of protonitrate 

 of mercury, protacetate of mercury is formed, and separates in bril- 

 liant scales ; formic acid, on the contrary, produces no effect in the 

 solution till heated, and then vivid effervescence takes place and me- 

 tallic mercury is precipitated. 



A cold saturated solution of acetate of lead is also a good reagent 

 for formic acid ; if the acid, either concentrated or dilute, be mixed 

 with it, crystals of formiate of lead are instantly produced in the form 

 of brilliant stars j the experiment may be made in a watch-glass : a 

 drop of concentrated solution of acetate of lead, added to a drop of 

 very weak formic acid, occasions the formation of crystals of formiate 

 of lead j the excess of acetate of lead may be removed by alcohol j 

 the formiate is insoluble in it. 



If formic acid, or, still better, formiate of soda, be added to a boiling 

 solution of perchloride of mercury, mercury is not precipitated, but 

 protochloride is quickly thrown down. Silver, gold and platirta are 

 precipitated from their solutions in a very divided state. 



M. Dobereiner remarks, that of all vegetable products, salicine 

 appears to furnish the greatest quantity of formic acid, when treated 

 with peroxide of manganese and sulphuric acid ; this acid is also 

 formed in putting concentrated muriatic acid in contact with prussic 

 acid, and leaving the mixture till the odour of prussic acid is no longer 

 perceptible. In this case the muriatic acid occasions the azote of the 

 prussic acid to combine with the hydrogen of the water present, to 

 form ammonia ; the oxygen liberated, combines with the carbon of 

 the prussic acid, and forms oxide of carbon ; and this last, at the 

 moment of its formation, combines with water to give formic acid. 

 —Ibid. 



ON PHOSPHOVINIC ACID, AND PHOSPHOVINATES. 



M. Pelouze prepares phosphovinate of barytes by the following 

 process : Mix equal weights of phosphoric acid, of the consistence of 

 a thick syrup, and alcohol 5 keep the mixture for a few minutes at a 

 heat of 140° to 175° of Fahr. ; at the expiration of 24 hours it is to 

 be mixed with 8 times its volume of water, and neutralized with car- 

 bonate of barytes reduced to as fine a powder as possible; the liquor 

 is afterwards to be boiled to get rid of the excess of alcohol ; it is then to 

 be allowed to cool to about 1 60° Fahr., and filtered. By cooling, a fine 

 white salt is obtained, which usually crystallizes in hexagonal laminae. 



The properties of this salt are as follows : it is inodorous j its taste 

 is disagreeable, being both salt and bitter, like that of all soluble ba- 

 rytic salts. When exposed to the air it effloresces but very slowly j 

 it is insoluble in alcohol or aether, and they immediately precipitate 

 it from solution in water. 



Third Series. Vol. 3. No. 13. July 1833. L 



