T U E J O U R N A L O F I i V D U S T R I A L A N D ENGIh’EERING
June, 1920
was given a n equal share of the contents of an inoculator which were about I S hrs. old. After inoculation the t a n k valves were all closed. When one of t h e tanks showed a gauge pressure of 2 lbs. t h e seal was emptied and refilled with fresh carbolic solution. The steam t o t h e gas line was then cut off, and the gas from t h e most active seed-tank allowed t o bubble through t h e seal. As the fermentations developed, the tanks were in turn connected t o t h e gas line. FERhIENTATIOX-During t h e fermentation period samples of the culture were examined a t regular intervals in t h e laboratory. The culture, when about IS hrs. old, was used as seed for a fermenter. It was allowed t o flow by gravity into t h e mash-filling line t o t h e fermenters, entering the line just beyond t h e point where t h e cooler discharged into t h e line. The connection was carried through into t h e larger line and turned against the stream of mash. I n this way t h e seed was thoroughly mixed with the much larger volume of mash. The contents of one seed-tank, j o o gal., were used t o inoculate a fermenter containing 2 4 , 0 0 0 gal. of mash. This was made possible by filling t h e fermenters in t h e manner described elsewhere. SuxhuRY-The whole of these operations are summarized in t h e following table, which shows t h a t each day eight stages had t o be prepared and controlled. Spores
MONDAY, 4: 00
P.M.
Tube-e?acuated
TUESDAY, 4: 00
P.M.
4.t.
/ Flask
i
l l *r.t. T.t.
T.t.
v Stock
\
Flask
I Culture-vessel
WEDXESDAY, 4 : 00 P.M.
THURSDAY, 4 : 00
P.M.
_____ I I I I
S.t.
S.t. S.t.
S.t.
d. d. 4. d. A.M.
S.t.
I
A.
slt. dt. S.t.I d. d. d.
SUNDAY
MEASUREMENT OF VISCOSITY OF PYROXYLIN SOLUTIONS’S 2
By E. F. Higgins and E. C. Pitman E. I.
DU
PONTDE XEMOURS & Co., WILMINGTON, DEL. Received October 15, 1919
IKTRODUCTION
The accurate control of t h e viscosity of pyroxylin solutions is of importance in nearly all industries making use of soluble cotton products. I t is of value t o t h e manufacturer t o have one instrument which can be used €or his entire range of solutions of both high and low viscosities, so t h a t all his results may be expressed in units which are directly comparable. The object of this investigation was the comparison of a number of commonly used types of viscosimeters, with respect t o accuracy, facility of manipulation, and range over which they could be used t o advantage. Although it is the usual industrial practice t o express viscosity as compared with some standard liquid, or as a purely empirical number, e . g., in seconds, we have calculated from our d a t a absolute viscosities as well, in order t h a t direct comparisons may be made between the various instruments. EXPERIXENTAL DETAILS
Comparisons of the following viscosimeters were made: A-100 cc. outflow pipette B-Tagliabue viscosimeter C-Inverted 100 cc. pipette D-Steel ball viscosimeter E-Stormer viscosimeter 1-With 150 g. counterweight 2-With 300 g. counterweight 3-With 600 g. counterweight
MONDAY
P.M.
RECORDS
Mention has already been made of t h e recording of operations in the plant and observations in the laboratory. I n addition, t h e following method was adopted t o assist in studying the causes of poor fermentations, due t o the weakness of the culture itself or t o contamination. Previous t o using any fermentation as seed, t h e last of its series of slides was made into a permanent preparation and labeled. A sample of t h e culture was collected in a large, sterile test tube and incubated. The sample and slides were kept until t h e corresponding fermenter had been distilled and t h e yields of acetone and alcohol calculated. Supposing t h a t a particular fermenter was not up t o t h e average it was not a n easy task t o go back over the eight stages, involving the use of several vessels, and locate t h e source of t h e trouble. The task was made easier by the fact t h a t it was possible t o return t o the sample and slides. If contamination had occurred in any stage the corresponding sample would by t h a t time have a very high acidity, and very possibly smears would indicate directly t h e presence of t h e contamination. Not only were mechanical faults discovered
587
in this way but also the personal factor was eliminated wherever possible. I wish t o acknowledge the assistance received from the members of t h e staff of the Fermentation Department during the erection and operation of t h e seed plant.
FRIDAY SATURDAY
CHEXISTRY
For calibrating liquids, sugar solutions, glycerol, and castor oil of known viscosities were used. The most viscous liquid was castor oil a t IO’ C., with a viscosity of 2,400 centipoises. (A centipoise is 0.01 times t h e c. g. s. unit of viscosity. I t is the viscosity of water a t 2 0 . 2 ~ C.) The absolute viscosities of t h e sugar solutions used were taken from t h e values given by Bingham and J a c k ~ o n . ~ The glycerol used for standardization was J. T. Baker’s C. P. product, diluted with water t o a specific gravity of 1.246j a t 20’ C., since this was t h e gravity of the most concentrated solution for which absolute viscosity values were available. Archbutt and Deeley’s4 values for the viscosities of glycerol solutions at 20’ C. were adopted. Castor oil appears t o be the most reliable calibrating liquid with a viscosity immediately above Published by permission of E. I. du Pont de Nemours & Company. Presented at the 58th Meeting of the American Chemical Society, Philadelphia, Pa., September 2 to 6, 1919. 8 Bureau of Standards, Sczentijic Paper 298, 83. 4 Bureau of Standards, Technologic Paper 112, 23. 1
2
T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
Vol.
No. 6
12.
TABLEI
NO.
zemp. C. 20 40 30 20 10 20 20 10
LIOUID
Viscosity CeFtipoises
Kinematic Viscosity 1.0 16.6 26.3 43.7 84.8 385 1027 2500
Specific Gravitv 0.9982 1.2756 1.2808 1.2859 1,2906 1.2465 0.9570 0.9622
1 .o
21.2 33.7 56.2 109.4 480 986 2418
Cc. PIPZTTE-
-100
100 c c . Pipette Discharge of 100 Cc. Sec. 19.5 32.8 40.5 57.1 94.0 410 1106
-
....
Inverted Steel 100 c c . Ball Tagliabue Pipette 10-in. Discharge Discharge Drop of 70 Cc. of 100 c c . of Ball Sec. Sec. Sec.
....
61.4 105.5 444 1220
..
----
V
B t
TAGLIABUE---
(F)
..
(1)
where V = viscosity in centipoises, d = density, = time of discharge in seconds, and A and B are constants depending on the instrument. By the method of W. F. Higgins2 we have derived values of A and B for the various outflow instruments. This method is based on the fact that when Equation I is divided by t the resulting equation is t h a t of a
as abscissas.
V
-
dt
as ordinates and
I t2
V A is the intercept on the axis of td
and B is the slope of the line. The values of V, d , and t are known and the curve can therefore be plotted and A and B determined from it. Table I gives the experimental d a t a from which curves were plotted and equations derived for the various instruments. (A) I O O cc. PIPETTE-This was the ordinary IOO cc. pipette contained in a glass water jacket. The reading recorded was the time of outflow (in seconds) of IOO cc. of solution between two graduations about 2 in. above and 2 in. below the bulb. When used with a solution, the time of discharge of which was 400 sec., it began t o drip after about 5 0 cc. had run out, indicating t h a t its use with pyroxylin solutions of equal viscosity containing volatile solvents would introduce inaccuracy. For solutions of Iower viscosity the IOO cc. pipette gave closely checking readings. Evaluating the constants A and B in Equation I 1 2
Bureau of Standards, Technologic Paper 112, 24. J . SOC.Chem. Ind., 83 (1913), 568.
.*.
2.4 4.9
... ... 14.9
52.9 112.9 262.0
.. .. .. .. 26.5 .. ..
-INVERTED 100 Cc. PIPETTE-B Kinetic Cort
-
;
t
straight line with values of
... ...
4.9 10.0 12.7 17.4 28.7 109.7 222 525
B
t h a t of glycerol, but there is considerable variation in different grades. The viscosity of the castor oil used in this work was taken from the values of Kahlbaum and Raber.’ The general form of equation calculating viscosity when a n outflow viscosimeter is used is d
-
-Stormer300 g . 600,g. 100 Rev. 100 Rev. Sec. Sec.
TABLEI1
.. 5
- = Ai--
27.5 117 322 665
....
E Kinetic CorKinetic Cor’ 1 (Standard) (Found) LIQUID At No. Centipoises (o,9jl) rection Centipoises co%,a rection 2 16.6 31.2 14.9 16.3 33.3 16.7 38.5 12.1 26.4 3 26.3 4 43.7 54.2 8.6 45.6 5i.4 . l0:4 5 84.8 89.3 5.2 84.1 91.8 6.1 6 385 389 1.2 388 386 1.4 7 1027 1051 0.4 1051 1061 0.5 8 2500 .. .. .. V = Viscosity of the calibrating liquid as obtained from ’standard tables. d = Observed density of the liquid. t = Observed time (seconds) of outflow. A and B are determined graphically from the curve obtained by plotting against i.
(y)
... ... ... ... ...
... ... ... ...
38.3
....
150 g.
m Sec.
(Found) Centipoises . . 16.6
..
.
..
4.i. 0
85.7 385 1060
6.2 1.5 0.5 0.3
90.7 386 1062 2190
..
