May 15, 1934
INDUSTRIAL AND ENGINEERING CHEMISTRY
extreme accuracy in measuring the time of reaction is not necessary. Slight error in time will result in practically no error in the ultimate alpha-cellulose result. The ratio of the sample to the reagent need not be exact, provided it is within certain limits (1 to 4 grams in 75 cc. of solution). The main precaution seems to be the use of carbonate-free alkali throughout the treatment. The suggested method has been tested on six commercial paper pulps, the alpha-cellulose content of which had been determined previously by the manufacturer, and the results are shown in Table IV and in Figure 3. TABLE Iv. DETERMINATION O F ALPHA-CELLULOSE IN COMMERCIAL PULPS MANU-
225
The author is indebted to Professor Bancroft for suggestions and criticism in this work. LITERATURE CITED (1) Jentgen, Kunststo,fe, 1, 165 (1911). (2) Neale, J. Teztile Inst., 22, T320 (1931). (3) R i t t e r e t al., IND.ENQ.CHEM.,Anal. Ed., 1, 52 (1929). (4) Sohwalbe, Papier-Fab., 23, 477, 697 (1925) [Chem. Abs., 20, 283, 502 (1926)]. (5) Waentig: Papier-Fab., 25, 112 (1921) [Chem. Abs., 22, 4974 (1928)]; 26, 64 (1928)[Brit. Chem. A h . , B47, 564 (1928)l. RECEIVED January 15, 1934. This work was done by the author in partial fulfilment of the requirements for the degree of doctor of philosophy a t Cornell University.
VALUE BY: Calculation Curve 83.60 83.75
84.02
PERCENTRESIDUE AFTER: 15min. 30min. 45min. 83.03 82.95 83.57 83.75 83.36 82.97 84.02 83.14 83.50
B
87.63
87.44 87.35
87.08 87.07
86.88
87.69
87.50
Determination of Sulfur in Benzene or Gasoline
C
91.26
91.01 91.15 91.06
91.10 90.76 90.67
90.80
90.75
91.21
91.25
Modification of A. S. T. M. Lamp
90.74
D
94.90
94.54
94.44
94.46
94.56
94.60
E F
98.54
97.87
97.70
97.63
97.89
97.97
98.42
97.33
96.97
96.94
97.28
97.10
FACTURER’S
PULP A
VALUE
H. 0. ERVIN Portland Gas & Coke Company, Portland, Ore.
I
N A RECENT article, Gillis ( 2 ) describes a modification of the standard A. S. T. M. lamp which provides for better control of the flame. A similar lamp of somewhat simpler construction has been in use in the author’s laboratory for about three years, and has been particularly successful with benzene and its blends, which ordinarily give more trouble than gasoline itself. The modified lamp is sketched in Figure 1. The glass tube A , which carries the wick as in the standard A. S. T. M. lamp, is made somewhat longer than usual to accommodate the sleeve B, which is a glass tube of slightly larger diameter. Because of the variation in tubing diameters, it has been found ALPHA-CELLULOSE advisable to make the sleeve of tubing sufficiently larger than CALCULATED DIFFERENCE IN Loss FROM: FROIM: 15 to30min. 30to45min. %/T 15 30 45 AVERAQE A to require some sort of flexible pack% % % % ing which provides the necessary fric17 7 12 97.99 97.94 97.99 97.97 tion to hold the sleeve in place. If a The average of these zero values is taken as the calculated glass-to-glass friction be used, sticking result. The method of calculating gets rid of any errors in is likely to occur a t a most inopportune plotting and drawing the curve and in estimating the extrapo- moment, with disastrous results. Even a smooth-sliding sleeve as made up may lated value. bind in use, because of expansion of SUMMARY the inner tube when heated by the comA preliminary study of the effect of concentration of alkali bustion of the material under test. A on the tentative standard method proposed by the Division of small piece of cotton wicking in the Cellulose Chemistry of the AMERICAN CHEMICALSOCIETY annular space serves as a satisfactory packing material. determination of alpha-cellulose was made. In operation the sleeve is simply In studying the effect of time on the treatment of cellulose moved up and down on the tube carrywith 17.5 per cent sodium hydroxide a characteristic curve was found which showed rapid losses in weight of cellulose a t ing the wick. If the flame is too high, first and soon approached a nearly constant value. A curve the sleeve is pushed up, and vice versa. of the same type giving the same nearly constant value was Very close adjustment may be made by FIGURE 1 rotating the sleeve slightly as it is found for 10 per cent sodium hydroxide. or down. moved up A method for the determination of alpha-cellulose has been The principle of flame control in this lamp is apparently proposed temporarily which eliminates exact specifications of time and sample-reagent ratio. The suggested method has the same as that employed in one of the lamps proposed by Edgar and Calingaert ( I ) who used a movable brass outer been tested on six commercial pulps. tube, but its construction is simpler, and the control, in the ACKNOWLEDGMENT author’s experience, more satisfactory. The six pulp samples used in testing the method suggested LITERATURE CITED above were furnished, together with the manufacturer’s data, (1) Edgar a n d Calingaert, IND. ENQ. CHEY., Anal. Ed., 2, 104 (1930). through the kindness of G. A. Richter of the Brown Company. (2) Gillis, Ibid., 5, 421 (1933). Other pulp stock was furnished by the Strathmore Paper RECEIVED DECEMBER 9, 1933. Company.
It was found more convenient and perhaps a little more accurate to calculate the percentage of alpha-cellulose back to zero time than to plot the data and estimate the value from the extrapolated curve. This was done by determining the loss for the 15-minute periods, 15 to 30 minutes’ reaction and 30 to 45 minutes’ reaction. The average of these two is designated A%/AT. Using the 15-, 30-, and 45-minute values as bases, the alpha-cellulose a t zero time can be calculated by adding to these values A%/AT, 2A%/AT, and 3A%/AT, respectively. For example, using the data from pulp F:
