V O L U M E 22, NO. 4, A P R I L 1 9 5 0
569
.7 nil. of hydrochloric solution and 2-ml. portions (equivalent to 20
nil. of the original sample) m r e used for the colorimetric determination. Electrometric results are shown for comparison, The results of analyses of several plant samples, shown in Table 111, indicate that the method is applicable to plant material. Temperature does not affect the results significantly over the range of 20’ to 35 C. Samples read after standing 45 minutes sho7ved no appreciable change at. the end of 4 hours. Samples of standard boric acid were included with each set of analyses made over a period of a year. During this time several different lots of sulfuric acid and carmine n-ere used but xithout effect on either the calibrat,ion curve or the recovery of boron from the stantlard solutions. This is interpreted to mean that the method is not sensitive to small changes in reagent, concentrations. The data obtained from standard boric acid solutions used in checking the precision of the method have been examined statisI
tically. A high order of reproducibility is indicated by the following values on 15 such sets of calibrations. Boron in standard boric acid solution, p.p.m. Percentage transmittance, mean Standard error of mean
1.0 86.2
*0.107
5.0 47.7 *0.097
10.0 23.3 +0.095
The accuracy of the method may be checked by the results in Tables I, 11, and 111. The standard error of the mean difference between the tvio methods shows that there is no significant difference a t the 5 % level. LITERATURE CITED (1) Austin, C. RI., and LIcHargue, J. S., J . Assoc. Ofice. Agr. Chemists, 31, 427-31 (1948). (2) Berger, K. C., and Truog E., ISD. ENG.CHEM.,.%NAL. ED., 11, 540-5 (1939). (3) Kazarinora-Oknina, V. A., Z(icodskuya Lab., 14, 263-5 (1948). (4) JI-ilc,ox,L. V.,Chronica Botan.. 6, 370-2 (1941). (5) Wilcox, L. V., ISD. ESG. CHEM.,AN.~L.,ED..4, 38-9 (1932). (6) Zorkin, F. P., J . A p p l i e d Chem. ( ~ . S . S . E . )9,, 1505 (1936). RECEIVED J u n e 11. 1949.
Determination of Chloroform and Bromoform . J. GORDON HANNA AND SIDNEY SIGGIA General Aniline & Film Corporation, Easton, Pa. A procedure for determining chloroform and bromoform is described. The haloform reacts with aniline in the presence of alkali and the halide ion formed by the reaction is determined. ]
