cipitation is not delayed in fluoridecontaining solutions suggest t h a t the hydroxide complexes which can cause the delay do not form. The precipitation reaction then involves the FeF+* complex and hydroxyl directly. The fluoride complex is a favorable one in that i t prevents the formation of the hydroxyl complexes without itself retarding the precipitation beyond the free acid equivalence point.
t i ) Hahn, H., Burow, F., 2. anal. Chem.
LITERATURE CITED
(1) Arden, T. V . , J. Chem. Sac. 1951,350.
(2) Booman, G. L., Elliott, M. C., Kimball, R. B., Cartan, F. O., Rein, J. E.. A N A L . CHE31. 30, 284 (1958). (3) Britton, H. T. S., J . Chem. Soc. 1925, 2148. (4) Connick, R. E., Hepler, L. G., Hughes. Z., Jr., Kury, J. IT.,Latimer, W. hl., Tsao, RL-S., J . Am. Chein. Sac. 78, 182T (1956). ( 5 ) Craig. T. J. I., J . Sac. Chem. I n d . (London), 30, 184 (1910). ( 6 ) Dodgen, €I., Rollefson, G., J. Am. Chem. Sac. 71, 2600 (1949).
151. 91 (1956). (8) K h k d v , P.‘A., Avseevich, G. P., 2 Elektrochem. 39, 884 (1933). (9) Miller, F. J., Thomason, P. F., ANAL. CHEM.31, 1498 (1959). :IO) Scott, W.,“Standard Methods of Chemical Analysis.” 5th ed.. Vol. 11, p. 2245, Van -Nostrand, New Jersey; 1954. RECEIVEDfor review October 19, 1959. Accepted June 27, 1960. Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, March 1, 1960.
Detection of Mercuric Ions with Potassium Antimono-Tartrate SIR: During experimentat,ion with phenols and with mercuric ions as catalyst, the noticeable reaction of mercuric ions with potassium antimonotartrate, K [C,H20&b(OH2)], took place in alkaline solution. This reaction may be used for detecting mercuric ions, as the following cxperiments show.
clear solutions. The nickel nitrate solution turned from light green to blue. Only the solution of mercuric ions gave the gray-black precipitate. E. A solution containing the cations mentioned in part B q n w the grayblack precipitate.
t i om the assumption that the antimonotartrate ions (11) in solution set up the following equilibrium, according to H. Remy (“Treatise on Inorganic Chemistry,” Vol. I, p. 671, Elseviei. Am~terdam,Yetherlands, 1956):
RESULTS AND DISCUSSION
. . . OH?
r OH-C-0-Sh -c-O\
I
r
EXPERIMENTAL
The following- reactions were studied a t 2-2’ C. A. Dissolve 2 grams of pota
