November 15, 1941
ANALYTICAL EDITION
fortunately, these results cannot be interpreted as substantiating HBgglund, because examination of Table I will show that in the cases of aspen sapwood, fire cherry sapwood, and yellow birch heartwood the acetyl content of the holocellulose represents 94, 99, and 98 per cent, respectively, of that in the original woods. Therefore, in three instances the results confirm those of Ritter and Kurth (16). Because of these contradictory results no clear-cut conclusion can be drawn regarding the location of the acetyl group. Possibly a portion of the acetyl groups in the other woods have been destroyed during the isolation of the holocellulose, owing to partial oxidation during chlorination and removal of the decomposition products during the pyridine-alcohol extraction.
Application of Results I n one instance the results of the present investigation have brought t o light information which otherwise might have escaped attention. It was noticed that the lignin content of fire cherry was exceptionally low, thus predicting a high carbohydrate content. Evaluation of the cellulose content yielded a n average figure of only 60 per cent. The difference between the cellulose and holocellulose contents suggested the presence of a considerable quantity of hemicellulose which was isolated and is now under investigation.
805
Acknowledgment The authors are indebted to H. P. Brown, New York State College of Forestry, Syracuse, N. Y., for collection and identification of the woods analyzed.
Literature Cited Benedikt and Bamberger, Monatsh., 11, 260 (1890). Cross and Bevan, Ber., 43, 1526 (1910). Dore, J. IND.ENG.CHEM.,12,472-6 (1920). Freudenberg and Harder, Ann., 433,230 (1923). Hagglund and Sandelin, Papierfabr., 32,253-5 (1934). Hawley and Norman, IND.ENG.CHEM.,24,1190 (1932). Iddles and Robbins, IND.ENO.CHEM., ANAL.ED.,5,55(1933) Klason, Ber., 53B,1864 (1920). Kline and Acree, Bur. Standards J . Research, 8, 25 (1932). Kurth and Ritter, J . Am. Chem. soc., 56,2720 (1934). O'Dwyer, Biochem. J., 23, 524 (1929). Powell and Whittaker, J . SOC.Chem. Ind,, 43,35 (1924). Pringsheim and Magnus, Z . physiol. Chem , 105, 179 (1919). Ritter and Fleck, IND.ENG.CHEM.,15, 1056 (1923). Ritter and Kurth, Ibid.. 25, 1250 (1933). Ritter and Mitchell, Forest Products Lab. Bull. (April, 1934). Ritter, Seborg, and Mitchell, IND.ENQ.CHEM.,.~NAL. ED.. 4, 202 (1932). Schmidt, Meinel, et al., Cellulosechemie, 13, 129-39 (1932). "U. S. Forest Products Laboratory Methods", U. S. Dept. Agr., Bull. (August, 1928). Van Beckum and Ritter, Paper Trade J., 18, 127-30 (1937). Zeisel, Monatsh., 6,989 (1885); 7, 406 (1886).
A Laboratory-Scale Flow Regulator LCVELIM; TU8C
VERNON H. CHELDELIN' ANI BERT E. CHRISTENSEN Oregon State College, Corvallis, Ore.
E
X P E R I M E N T S conducted in this laboratory involving the slow transport of gases have made necessary the use of a device for regulating their flow. Although a few designs intended for laboratory use are reported in the literature (1-4), all possess certain limitations in regard to expense, simplicity, reproducibility, and personal supervision. T o meet all these factors, the conditions of which were imposed b y a problem under investigation, i t was necessary to design a regulator. The apparatus (Figure 1) is fashioned from the escapement wheel, 'cv, and the lever, L,of a pendulum clock. A perforated strip of metal, S , 30 inches long and 0.75 inch wide, is welded to the end of the escapement lever. A weight, M , is then attached to the lower end of the metal strip, producing a typical pendulum with a relatively long period of vibration. A drum, D,is fastened on the axis of the escapement wheel, and is then wound with a stout cord or wire. A leveling bulb containing mercury or some other liquid is now suspended from the drum by the cord. The weight of the leveling bulb thus acts on the escapement wheel and provides the force necessary to keep the pendulum in motion. As the wheel turns and the drum unwinds, the leveling bulb is lowered slowly, reducing the pressure within a bottle to which the leveling bulb is connected and causing gas to flow into the bottle. T h e purpose of the pendulum is to maintain a constant lowering of the leveling bulb. The weight of the bulb increases as i t fills with liquid, but the effect on the pendulum is one of increased amplitude of vibration rather than shortening of the period. Present address, Department Austin, Texas. 1
of Chemistry, University of Texas,
1"'
.EVELING TUBE
EALANCINC WEIGHT -
rPENDULUU
ELEVATION
FIGURE1. FLOW REGELATOR
Literature Cited (1) Brimley, R. C., J . Sci. Instruments, 14, 102 (1937). (2) Chalkley, Lyman, Jr., IND. ENG.CHEM.,ANAL.ED., 1, 74 (1929). (3) Gregory, F. G., Ann. Botany, 47, 427 (1933). (4) Hiby, J. W., Physik Z.,39, 167 (1938).
