IXD USTRIAL AND ENGINEERING CHEMISTRY
476
generally the case with alcohols and glycols. It is probable that, like ethylene glycol, diethylene glycol forms a molecular complex with water, and this has a positive heat of solution. SOLUBILITY-At ordinary temperatures diethylene glycol was found to be freely miscible with water, methanol, ethanol, ethylene glycol, glacial acetic acid, acetone, furfuraldehyde, pyridine, glycol diacetate, chloroform, nitrobenzene, and aniline. It is immiscible with ether, benzene, toluene, carbon bisulfide, and carbon tetrachloride. An attempt to determine the molecular weight of diethylene glycol with benzene as a solvent indicated a solubility of 0.51 gram of the former in 100 grams of the latter a t 0" C. INFLAMMABILITY-Like glycol, diethylene glycol is nonflammable in the air a t ordinary temperatures. If, however, each is slowly heated in a shallow dish, glycol becomes in-
Vol. 19, No. 4
flammable in the air a t a temperature of 100" C. and diethylene glycol a t 130" C. Each burns with a clear, bluish flame. HYGRoscoPIcITY-Diethylene glycol is very hygroscopic and appears to be even more so than ethylene glycol. A sample in a flat vessel was placed in a closed space over water a t room temperature and found to absorb more than its own weight of water in 9 days. De Forcrand foundI3 that ethylene glycol appeared to reach a maximum after absorbing 60 per cent of its own weight in 2 weeks. STABILITY-Admixture with water does not appear to hydrolyze diethylene glycol. Determinations of molecular weight with water as the solvent in an 8 per cent solution gave results of 99.3 and 118.8, which would indicate that no hydrolysis to ethylene glycol had taken place. 13
Comfit. rend., 132, 688 (1901).
Viscosity of Cellulose Solutions' Modifications in Small's Cuprammonium Method By C. R. Genung SOUTHERN CHEMICAL COTTON Co., CHATTANOOGA, TENN.
HE increasing use of cellulose as a raw material in the
T
industries has made manufacturers, especially those making nitrocellulose, realize the importance of a reliable method for determining its viscosity. The most accurate method so far developed which is applicable to all grades of cellulose is that described by Small.2 He uses a cuprammonium solution containing 3.0 * 0.2 per cent copper by weight and 165 grams of ammonia per liter, and his cellulose solution contains 2.5 or 5 grams of cotton in 97 cc. of solution, depending on the probable viscosity of the cellulose under examination. The cuprammonium solution is made by bubbling air up through a tower containing clean copper turnings over which 28 per cent ammonia 8
Received December 31, 1925. Resubmitted January 3, 1927. THISJOURNAL, 17, 515 (1925).
containing 1 per cent sucrose is allowed to trickle. To fill the cellulose bulb with the cuprammonium solution the vacuum is created by means of a mercury reservoir similar to that used in gas analysis. The method proposed by the writer is a modification of Small's procedure, which gives greater ease in manipulation and increased accuracy of results. The vacuum is created by means of a filter pump and the air is removed from the bulb by repeatedly washing with hydrogen. Electrolytic hydrogen of 99.6 per cent purity gives excellent results. Note-If a Kipp generator is used for the generation of hydrogen, it will be necessary to use an elevated reservoir for the storage of the solvent.
The apparatus has been further simplified by replacing the cuprammonium storage bulb and buret by a measuring pipet, filled by using hydrogen under a pressure of 50 to 75 mm. of mercury. By enlarging one end of the dissolving bulb so that it takes a No. 4 rubber stopper the time required to fill the bulbs with the weighed cotton sample is shortened. I n the writer's experience greater - accuracy is obtained by limiting the range of copper concentration of the cuprammonium solution to between 2.95 and 3.05 per cent by weight. Except for these modifications the procedure is similar to that given by Small. The modified apparatus is shown in the accompanying figure. Viscosities of Cellulose-Cuprammonium Solutions by Original a n d Modified S m a l l Method
.
SAMPLE
1
5 25 84 176
5
680
2 3 4
Apparatus for Filling Dissolving Bulbs for Use with Hydrogen under Pressure
MODIFIED METHOD (1) (2)
5 24 84 172 720
ORIGINALMETHOD (1) (2) 6
24 89 167 671
6 27 86 162 640
I n order to compare the accuracy of the two procedures, 2.5-gram samples were dried and the viscosities of portions of each sample determined by both methods. The figures in the table show not only the relative accuracy of the two methods, but also that the results of two determinations of the modsed method agree more closely than those by the original method. The higher viscosities by the modified method are due to the complete removal of oxygen by this method.
April, 1927
INDUSTRIAL AND ENGINEERING CHEMISTRY
477
The Destructive and Preservative Effects of Neutral Salts upon Hide Substance-II'pz By Arthur W. Thomas and Margaret W. Kelly DEPARTMENT OF CHEMISTRY, COLUMBIA UNIVERSITY, XEW Y O R K , N . Y.
Solutions saturated with varying mixtures of sodium in each instance. While the chloride and sodium sulfate show less catalysis of p H values of saturated salt tain peculiar differences hydrolysis of hide powder than sodium chloride alone. solutions may be of doubtful in the hydrolytic catalyAt room temperature a solution saturated with a salt value, the same were meassis of hide powder by salts mixture in the proportion of 5 mols NaCl to 1 mol ured and are entered here as a were revealed. The alkali Na2S04 preserves hide powder about as well as one matter of record. The p H and alkaline-earth h a l i d e s saturated with sodium sulfate. Saturated sodium values of the solutions diluted exerted a strong hydrolytic sulfate solutions show better antihydrolytic action ten times are likewise given. action, the latter much more at high temperatures than at low temperatures for the These figures lead to the than the former, iodide and reason that at higher temperatures much more sodium conviction that differences in b r o m i d e m u c h more than sulfate is contained in a saturated solution. Calcium hydrolytic action of the salts chloride, while the sulfates of chloride is very destructive in its action. Sodium are not pH effects. sodium and magnesium were chloride also catalyzes the hydrolysis, but to a much The results of the analyses shown to exert marked inhibiless extent. When these salts are mixed together, the are recorded in Table I1 and tion to the destructive action hydrolytic action is much less than with sodium shown graphically in Figure 1. of water on hide substance. chloride alone. In other words, the addition of calThe expected increased hyThese experiments were concium chloride to sodium chloride renders the latter a drolysis due to rise in temperducted in a manner such as better hide preservative. ature is shown in all cases exto exclude bacterial action. ceBt sodium sulfate. ExamiWhile not identical in all respects, the results obtained closely resembled the effect of nation of the results found for this salt, especially for the longer salts in increasing the solubility of certain amino acids in digestive periods, shows the hydrolysis order to be 7" C. >room temperature > 37.5" C., the degree of hydrolysis at the latter water.4 I n this investigation there is included the effect of (1) temperature being practically zero. This anomaly is exsaturated solutions of some of the more common salts a t plained upon consideration of the concentrations of sodium three temperatures, ( 2 ) saturated solutions of sodium chlo- sulfate in solutions saturated a t the three temperatures. ride-sodium sulfate mixtures a t two temperatures, and (3) The saturated solution a t 37.5" C. contains almost twice saturated sodium chloride solutions containing calcium as much sodium sulfate as that saturated at room temperature and about seven times that of the 7" C. saturated solution. chloride. Fifty-gram portions of American standard hide powder Since the hydrolytic action is practically zero in the warm were covered with 1-liter portions of the chemically pure salt saturated solution, containing seven times as much of the solutions in stoppered bottles. I n view of the danger of salt as in the cold saturated solution in which hydrolysis was complications through bacterial action in the distilled water appreciable, conclusive corroboration of the statement made control, it was covered with toluene as inhibitory agent. in the first paper3 is found-i. e., sodium sulfate is a hide Toluene was not added to the saturated salt solutions. The preservative. This salt is an anticatalyst to hydrolytic acbottles were stored in the dark a t the temperatures noted. tion. It is to be emphasized at this point also that no antiThey were shaken once daily during the first 4 weeks, and septic means other than sodium sulfate were used. thrice or twice weekly thereafter. At the intervals of time Table I-Salt Solutions Employed noted in the tables, specimens of the solutions were withP H O F SATURATED P H OF DILUTE drawn by pipet', filtered through dry ordinary filter papers, SALT SOLUTION SOLUTION and a measured portion of the filtrates was subjected to the NaCl 4.6 Kjeldahl process for determination of nitrogen. From the KC1 5.6 CaClz 3.6 figures so obtained the percentage of hydrolysis of the hide MgC12 3.4 NanSOa 5.0 powder was calculated. Corrections for the decrease in volume caused by these withdrawals were made in all subsequent calculations. There was none of the familiar eviMcLaughlin and Theis5 hare corroborated the writers' dence of bacterial action in any case. earlier findings that sodium sulfate incites less hydrolysis of hide substance than sodium chloride. They criticize Effect of Saturated Solutions of Various Salts Thomas and Foster's suggested use of Glauber's salt instead The salts listed in Table I were used. Saturated solutions of common salt for the commercial salting of hides as of a a t the three temperatures-7' C. (45" F.), room temperature "highly speculative nature" and show that sodium sulfate is 20-25' C. (68-77' F.), and 37.5" C. (99' F.)-were prepared not a good antiseptic. Their paper shows that bacteria grow in saturated sodium sulfate solutions in contact with hide 1 Presented before t h e Division of Leather and Gelatin Chemistry under t h e titles "Hydrolysis of Hide Powder by Saturated Salt Solutions," substance at 20" C. It is hoped that they will repeat their by A. m'. Thomas, a n d "Hydrolysis of Hide Powder b y Saturated Mixtures measurements a t 37.5' C., since the present writers are conof Sodium Chloride and Sodium Sulfate" by M . W. Kelly a t the 72nd Meetvinced of the absence of bacteria in saturated solutions of the ing of t h e American Chemical Society, Philadelphia, Pa., September 5 t o 11, sulfate a t this temperature. 1926. 2 Contribution Iio. 533 from t h e Chemical Laboratories, Columbia The digestions a t the lower temperatures also appeared to University. be free from organisms, but the results of NcLaughlin and 8 Thomas and Foster, THIS JOURNAL, 17, 1162 (1925).
I
K A previous paper3 cer-
' Pfeiffer a n d Wurgler, Z. physiol. Chem., 97, 128 (1916).
6
Collegium, No. 678,431 (1926).
