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tiiy found is corrected for the apparatus blaGk, and for the “preformed” amnionia determined directlv uDon a fiarntde of the dried tissue, not upbn the extract. Results ihat are probably somewhat more trustworthy from the chemical point of view are to be obtained from analyses of extracts from the by the ether cytolysis method. In this magnitude of the sampling error may beco
s that the recovery of of glutamine and asp quantitative under the conditions described, and Table V illustrtites the reproducibility of the resultb on several plant tissues. Literature Cited (1) Bosshard, E.,2.anal. Chm., 22,329 (1883). (2) Boussingault, J. B., Ann. china. phys., (3)29, 472 (1850); reprinted in “MBmoires de chimie agrioole et de physiologie,” p. 285, Paris, 1854; and in “Agronomie, chimie agricole et physiologique,” 3,p. 233,Paris, 1864. (3) Castoro, N., 2.physiol. Chem., 50, 625 (1907). (4) Chibnall, A. C., J . Bid. Chm., 55,333(1923). (6) Chibnall, A. C., and Westall, R. G.,Biochsm. J., 26, 122 (1932). (6) Conway, E.J., and Byme, A,, Ibid., 27,419 (1933).
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2. physiol. Chena., 37, 161 (1902) , Bell, R. D., J. Biol. Chem., 29,329 (1917). (8) Folie, O h and (9) Folin, O.,and Denis, W., Ibid., 11, 527 (1912). (10) drover, C. E., and Chibnall, A. C., Biochena. J.,21,8 (11) Klein, G.,and Taubock, K.,Biochem. Z.,241,413 (1931). (12) Koch, F. C., and McMeekin, T. L., J . Am. C h m . Soc., 46,2066 , (1924). (13) Kostychev, S., “Chemical Plant Physiology,” tr. by C. J. Lypn, p. 315,Philadelphia, P. Blakiston’s Son & Co., 1931. (14) Longi, A., Versuchs-Stat., 32, 15 (1886). (15) Neubauer, C., “Anleitung zur qualitativen und quantitativen Analyse des Harns,” p. 113,Wiesbaden, Kreidel, and Niedner, 1854. (16) Schlenker, F. S.,Plant Phusiol., 7, 685 (1932). (17) Sohlossing, T.,Ann. china. phys., (3)35,153 (1851). (18) Urbach, C.,Biochm. Z.,259, 351 (1933). (19) Urbach, C.,Mikrochmie, 11, 37 (1932). (20) Vickery, H.B., and Pucher, G. W., J . Biol. Chsm., 83, 1 (1929). (21) Viokery, H.B., and Pucher, G. W., Zbid., 90,179 (1931). (22) Vickery, H. B., Puohet, G. W., Clark, H. E., Chibnal!, A. C., and Westall, R. G., in press. (23) Wirth, H.E.,and Robinson, R. J., IND.ENQ.CHEM.,Anal. Ed., 5, 293 (1933). (24) Wurster, C., Ber., 22, 1901 (1889). R E C ~ I V EFebruary D 14, 1935. The expenses of this investigation were shared by the Connecticut Agricultural Experiment Station and the Carnegie Institution of Washington.
An Automatic Pix,et for Rax,id Deliverv I
W. T. FORSEE,
I
4
JR., P. J. THOMPSON, and C. B. POLLARD, University of Florida, Gainesville, Fla.
I
N PERFORMIXG quantitative experiments it is often advantageous to measure a volume of solution quickly and also to keep it free from some undesirable atmospheric gas. A pipet which does this quickly and efficiently, shown diagrammatically in Figure 1, has been used by the authors to deliver 0.5 N sodium hydroxide free from atmospheric carbon dioxide.
DETAILS
OF-
STOPCOCK A
The simplicity of this apparatus is manifest by the fact that one stopcock, A , controls all operations except emptying the pipet. This stopcock plug is a regulation 2-mm. T-bore having special additional drilling. A diagonal hole is drilled from the point just opposite the vertical arm of the T, meeting an axial drilling from the end as shown in 4. The jet, V , is not necessary but is very convenient in case the pipet should overflow. The intake, I, is attached to a compressed air line, which must be equipped with a Bunsen valve and a scrubber which will remove moisture and carbon dioxide. The pipet may be attached to the solution bottle, 8, by means of either a rubber stopper or g. ground-glass joint. R is a reenforcing rod. B is an enlarged place in the line to lessen the chances of overflow. The jet, J, controls the level of the meniscus line, M . Unless the pipet is small, some additional support is necessary. ’The authors used a clamp such as that shown by the Fisher Scientific Company, No. 5-778. One end was attached to the neck of the bottle and the other end to the body of the pipet. The use of a bottle as a container for the solution is proposed because it allows the entire set-up to be moved a t any time. The specially drilled stopcock is the original and most unique part of the apparatus and any other part of the set-up could easily be changed so as to be more adaptable to the needs of the user. To start operating the pipet set stopcock A as shown in position 1. This admits compressed air through I and D into the bottle, thus exerting a pressure on S and forcing the solution through E and J into P. At the same time, the pressure built up in P is released through B and C and out through V . After the level of the liquid in P has risen above M , the stopcock is turned through a one-fourth turn to position 2. This equalizes the pressure above the liquids in P and in the bottle, thus allowing the excess solution to siphon back from P into S until the liquid level corresponds to M. A is then turned t o position 3 and F is opened. The air pressure is thus used t o force the solution out quickly. If quick delivery is not required, A may be left at position 2 and the pipet will drain freely. When the pipet is not in use, E should be closed and A set at position 2. This excludes outside air from any part of the apparatus.
5&>?\, w
FIGURE1. DIAGRAM OF PIPETAND STOPCOCK
RECEIVED March 16, 1935.
