BY F. K . C . \ M E R O S A X D IT. 0 . R O B I S S O N
There is verj- little mention of ferric oxalates in the literature. G . Lemoine’ found t h a t oxalic acid and ferric chloride react very slon-ly with one another at ordinary temperatures hut rapidl!- a t temperatures abol-e 100’ in a sealed tube, He does not, honei-er, describe the solid phase he obtained, since the object of his research \vas the rate of reduction of ferric chloride. Iiosenheim3 found that freshly precipitated ferric hydroxide dissolved in oxalic acid to form a deep yellom-, syrupj- solution of the composition Fe,O,. ,$,O,xH,O. In connection with studies of the action of 1-arious acids upon ferric hj-droxide, the system Fe,O:,, C.,O, and H,O has been studied in part a t 2 joC. Oxalic acid solutions of \-arious concentrations were put in contact x i t h ferric hj-droxide and a t the end of three months the solutions and ,, remaining solid phases v-ere anal\-zed. I he iron \vas determined in the usual gra1-iinetric manner. The oxalic acid was determined b j r titration Irith permanganate. In the analysis it \vas noticed t h a t approximately one-tenth of the total amount of permanganate used for each determination was immediatelq- reduced in the cold. It was necessary t o heat the liquid t o accomplish the rest of the reduction. From these facts it appears t h a t about one-tenth of the oxalic acid had disappeared in reducing the iron t o the ferrous condition. The analytical results are gix-en in Table I , and show, v h e n plotted, t h a t the solubility of the ferric oxide is directly proportional to the concentration of oxalic acid, and t h a t no definite basic ferric oxalate is formed from solution a t 2 j O C. -It all concentrations, the solution contains more iron than is I
i
I’uhiislietl I)! pe~-i~iission oi tlie Secretary oi .Agricul~ure Conilites rendus, 116,9Si--2 (1893).
Zeit. anorg. Clicin.,
1 1 , 1 ~ j - 2 3(18~16,~. ~
equivalent t o the oxalic acid present, but as is usual with solutions of ferric salts, all these solutions had an acid reaction by the ordinary tests.
T.~IH,E I Showing the solubilit! of ferric h! drovid i n aqueous solutions of oxalic acid and the composition of the solid phases n i t h adhering solution. -
-
__
~~
Sp. gr.
Percent Fe,O, - ~-
-
_
~
-_ .~
Solid - adhering solution
Sol ut1011 __
.
-~
~
Perceiit '2-0, Percent Fe.0, I-. __ _ _ _ ~ ~
Percent C,O, -
3.01 -
4.02
