1891.] 105 [Warwick. 



MANGANOUS FORMATE. 



This salt was prepared from manganous carbonate precipitated from a 

 hot solution of manganous sulphate, by means of sodium carbonate added 

 to alkaline reaction and decanted as rapidly as possible until free from all 

 except very slight traces of soluble salts. It was then dissolved in formic 

 acid and allowed to crystallize very slowly. The crystals thus obtained 

 were allowed to recrystallize. The crystals are small, pale reddish 

 monoclinic prisms, soluble in fifteen parts of water, and contain two mole- 

 cules of water of crystallization. 



NICKEL FORMATE. 



A solution of nickel chloride was treated with a slight excess of sodic 

 hydrate, washed several times by decantation with hot water, dissolved in 

 acid and evaporated down. A greenish crust formed, made up of very 

 small, bright, green needles Ni (C HO 2 ) 2 + 2 H 2 O. 



FERRIC FORMATE. 



Ferric chloride was treated with excess of a solution of ammonia, 

 washed with hot water, and allowed to digest in formic acid at a tempera- 

 ture which was not allowed to exceed 70, until the hydrate of iron had 

 completely dissolved, which required several hours. The deep-red solu- 

 tion was allowed to crystallize by spontaneous evaporation. Yellowish- 

 red needles, crystallizing in radiating tufts, separated out, which formed 

 a light, loose, coherent powder. When dried at a moderate temperature, 

 it was readily soluble in cold water with an acid reaction. Aqueous solu- 

 tions on warming became turbid from the partial decomposition of the 

 salt into ferric hydrate and free acid. A similar decomposition takes 

 place in solutions at ordinary temperatures after standing for some time. 

 (The foregoing salt was made in preference to ferrous formate on account 

 of its greater solubility.) 



MERCURIC FORMATE. 



Mercuric oxide was dissolved in formic acid, but on warming the solu- 

 tion slightly it decomposed into the very sparingly soluble white mercur- 

 ous formate, carbon dioxide and formic acid, according to the following 

 equation : 



2 Hg (C H0 2 )' = Hg 2 (C HO. 2 ) 2 + C HO 2 H -f CO 2 and 

 Hg 2 (C H0 2 ) 2 = 2 Hg -f C H0 2 H + CO 2 . 



The precipitate was gray in color from the presence of free mercury. 

 The tendency to decompose is such that in solution at ordinary tempera- 

 tures these changes take place readily in the light and, with more slow- 

 ness, even in the dark. The"ous" salt comes out in minute shining 

 crystals, very insoluble in water, and on continuous warming becomes 

 entirely converted into Tree mercury. The formates of silver, bismuth 



