V O L U M E 21, NO. 10, O C T O B E R 1 9 4 9 this is transferred to a centrifuge tube and water added to make approximately 40 ml. of solution. Two drops of bromothymol blue me used as an indicator instead of phenol red; 0.8 ml. of calcium phosphate solution is added and the analysis is continued previously described. Higher concentrations than the range specified are easily analyzed by using aliquot parts or by dilution. An aliquot can conveniently be taken while the sample is in liquid form in the centrifuge tube prior to the precipitation of phosphates. The above procedure does not depart from standard techniques used by the analytical chemist, and elaborate optical adjustments for the spectrographic procedure are avoided. This
1283 enables the spectrographer to perform the analyses on the prepared samples with speed and facility. The short time required for setup is particularly advantageous in an industrial laboratory where many different problems are encountered. LITERATURE CITED
(1) Cholak, J., and Hubbard, D. M., ANAL.CHEM.,20, 73 (1948). (2) Ibid., 20, 970 (1948). (3) Churchill, J. R., IND.ENG.CHEM.,ANAL.ED., 16, 11 (1944) (4) Leichtele, P. A., J . Optical SOC.Am., 34, 8 (1944).
RECEIVEDjsnrlary 7 , 1'149.
All-Metal Needle Valve of the HershbergSouthworth Type Committee for the Standardization of 3Iicrochemical Apparatus Division of Analytical and Micro Chemistry, AMERICANCHEMICALSOCIETY A L STEYERMARK, Chairman HUFFMAN, J. A. I
