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(5) Berl and Kunze, Z. angew. Chem., 45, 669 (1932). (6) Berl-Lunge, “Chemisch-Technische Untersuchungsmethoden,” 8th ed., Vol. 5, p. 735, Berlin, J. Springer, 1933. (7) Ibid., Vol. 3, p. 1292. (8) Berthelot-Gaudechon, Compt. rend., 153, 1220 (1911); 154, 201, 514, 1597 (1912). (9) Brame, J. SOC.Chem. I n d . , 31, 159 (1912). (10) Briotet, M e m . poudres, 18, 185 (1921). (11) Duclaux, Bull. soc. chim., 29, 374 (1921). (12) Du Pont, Berl-Lunge “Chemisch-Technische Untersuchungsmethoden,” 8th ed., Vol. 3, p. 1291, Berlin, J. Springer, 1933; 2. ges. Schiess- u. Sprengstofw., 23, 340 (1928). (13) DuprQ, Ann. Rept. Inst. Erplosives, 32, 6 (1907); “Treatise on Service Explosives,” p. 128, London, 1907. (14) Dupr6. Ann. Rept. Inst. Erplosives, 28, 27 (1903). (15) DuprQ,“First Rept. Dept. Comm. on Heat Test as Applied to Explosives,” London, 1914; Marshall, “Explosives,” p. 644, London, J. & A. Churchill, 1917. (16) DuprQ Ann. Rept. Inst. Ezploaives, 29, 28 (1904). (17) Egerton, J . SOC.Chem. Znd., 32, 331 (1913). (18) Farmer, J. chem. soc., 117, 1432 (1921). (19) Fric, Compt. rend., 154, 31 (1912). (20) Goujon, M e m . artillerie f r a n p i s e , 8, 837 (1929). (21) Guttmann, 2.angew. Chem., 1897, 265; 1898, 1104; 1900, 592. (22) Hansen, Dansk Artilleri Tids., 12, 129 (1925). (23) Hess, Mitt. A r t . u. Geniew., 10,349 (1879). (24) Ibid., 14, 92 (1883). (25) Ibid.. 10, 360 (1879). (26) Hodgkinson and Coote, Chem. News, 91, 194 (1905). (27) Hoitsema, Z. angew. Chem., 12, 705 (1899); 2. physik. Chem., 27, 573 (1898). (28) Jacqut., Kast-hletz, “Chemische Untersuchung der SprengZiindstoffe,” p. 246, Brunswick, Friedr. Vieweg & Sohn, 1932. (29) Jahresber. Milittirversuchsamt, 3, 20, 69 (1896); 4, 34 (1897). (30) Lenae and Metz, 2. ges. Schiess- u. Sprengstofw., 23, 340 (1928).
VOL. 10, NO. 4
(31) (32) (33) (34)
Lenze and Pleus, Ibid., 14, 317 (1919). Metr, Ibid., 21, 186 (1926); 24, 245 (1929). Mittasch, 2.angew. Chem., 16, 929 (1903). Nauckhoff-Philip, “Researches, etc., Ingeniorsvetenskaps Akademien,” Heft 28, Stockholm, 1924. (35) Obermiiller, Mitt. Berl. Bezirksuer, Ver. deutsch. Chem., 1, 30 (1904). (36) O’Hern, J. U. S., 40, 148 (1913). (37) Patart, Mem. poudres, 15, 44 (1909/10). (38) Pleus, 2. ges. Schiess- u. Sprengstofw., 5, 121 (1910). (39) Robertson, J. SOC.Chem. Ind., 21, 823 (1902). (40) Robertson and Napper, J . C h a . Soc., 91, 769 (1907). (41) Robertson and Smart, J . SOC.Chem. Ind., 29, 130 (1910). (42) Schaeffer and Treub, 2. physik. Chem., 81, 308 (1913). (43) Silberrad. Ann. Rept. Inst. Erplosioes, 30, 28 (1905). (44)Spica, A t t i Reale Ist. Scienze, p. 27, 1899. (45) Sy, J. Am. Chem. Soc., 25, 549 (1903); 2. angew. Chem., 18, 940 (1905). (46) Taliani, Gazz. chim. itd., 51, 1, 184 (1921). (47) Taylor, IND. ENQ.CHEM.,16, 1185 (1924). (48) Thomas, Mitt. A r t . u. Geniew., 15, 203 (1884). (49) Vieille, Monk “La poudre B e t la marine nationale,” p. 134, Paris, 1912; RQglements de reception des nitrocelldosee et poudres dans les poudreries franpaises. (50) Weeren-Schellbach, Mitt. A r t . u. Geniew., 10, 349 (1879); 14, 92 (1883). (51) Will, J . SOC.Chem. Ind., 21, 819 (1902); Mitt. d. Zcntralst. wiss.- techn. Unters., 2 (1900); 3 (1902); 2. angew. Chem., 14, 743, 774 (1901). (52) Ibid., 45, 669 (1932). (53) Willcox, J. Am. Chem. Soc., 30, 271 (1908). RECEIVED November 1, 1937. Presented before the Microchemioal Section N. C.. April 12 t o 15, 1937. a t the 93rd Meeting of the American Chemical Society, Chapel Hill,
A Procedure for Microfusions CHARLES VAN BRUNT, General Electric Co., Schenectady, N. Y.
D
URISG a recent investigation of a series of transformation products available only in very minute quantities,
using microchemical procedure throughout, insoluble residues
of t h e order of 0.1 mg. in weight were obtained, and it was important to obtain at least a qualitative knowledge of their identity. Scantiness of material required that everything possible be done on a single sample. In such a situation the analyst naturally turns t o a fusion A search of microchemical literature, however, revealed no record of quantitative analytical fusions with such small amounts. Half-milligram charges could not be handled in even t h e smallest available platinum crucibles without danger of loss, chiefly because of the tendency of t h e fused material to creep. Electrically heated platinum ribbon is subject to t h e same difficulty to a high degree. Finally a modified bead procedure proved highly satisfactory. Each residue was obtained in the course of the analysis as a thoroughly washed powder driven into the apex of a microcentrifuge tube. It was withdrawn as a slurry by means of a capillary pipet and deposited upon a platinum ribbon 0.025 x 1.50 mm. which was gently heated by a current. By careful manipulation of the pipet it was easy to concentrate the dried material in about 4 mm. of the ribbon length, all on the upper side. It adhered well enough for the subsequent handling. The end of a piece of 0.508-mm. (0.020-inch) platinum wire was bent into an elongated crook slightly smaller in external dimensions than the section of ribbon carrying the dry residue. This crook was filled Kith the desired amount of flux (KNaC08) by the familiar process of dipping and fusion in the microflame. The section of ribbon was then cut out with scissors and received on the corner of a slide. The flux on the wire was next re-fused
and quickly touched to the deposit on the ribbon section held close t o the flame on its slide. Ribbon and all were thus picked up. Upon reheating, capillary action a t once drew the section into a symmetrical position on the crook and held it there, permitting thorough contact of sample and flux during the subsequent fusion, even with a moderate blast. No tendency to creep was observed. Where creeping occurs, however, it can usually be prevented by using a wide flame with its center directed upon the wire shank beyond the fusion so that the heat gradient is always downward t o the fusion.
A decided advantage of this procedure is t h a t t h e fusion can be dissolved from the wire directly in tubes as small as 2 mm. in bore, thus doing away with the loss or dilution involved in transfer from a crucible. T h e procedure is not adapted t o pyrosulfate: The excess sulfuric anhydride is lost too rapidly and the direct flame causes reduction. Quartz tubes are best for this. With alkaline carbonate a good fusion may be obtained over the direct microburner flame without important contamination from the sulfur content of t h e gas. RECEIVED November 16, 1937.
Correction An error was made in printing in our February issue the paper by Foulke and Schneider entitled “The Microtechnic of Organic Qualitative Analysis.” In Figure 4, on page 106, tubes A and B should have been shown with open, rather than closed, ends.
