ANALYTICAL EDITION
February, 1945
99
In order to correct for volatile material other t h a n slaihol in the beer, an unfermented sample of the wood-sugar solution may be distilled and thc percentage of apparent alcohol determined in the usual way. The alcohol concentration of 'he beer is then corrected by subtracting the apparent alcohol concentration of the wort before iermentation from the value obtained after iermentation. I n the raniples tested, tiris apparent alcohol coneentrstian of the wort before fermentation has proved to b e a mal! negstive value. The alcohol yield as detcmincd bj. the specific gravity method may be checked by the use of an immersion reiraetometer, using the tables provided by the Association of Official Agricultural Chemist.. LITERATURE W E D (11 Assoc. Oficial Agr. Chem.. Official and Analysis, 5th ed., D. 49R (19401
Tentative Methods ol
ibid., p i . 500-1. Benedict, S. R.,J . B i d . Chem.. 3, 101 (1907): J. A m . .&Id, Assoc., 57. 1193 (1911). (4) Britton, H. T. 9.. and Phillips, L., Analyst. 65.18 (1940). (51 Brown and Zerhan. "Sugar Analysis". 3rd ed.. New York. John Wile)- R- Sone. 1941. (6) Hngglund, E., Klingstedt, F.. Rosenqvist. T . , and Urban. H., 2. phyaioi. Chem.. 177, 248-63 (19281. Krersman F. W.. U. S. Dopt. Agr., Bull. 983 (1922). Lane and Eynon, 3. SOC.Chem.Znd..42, 143T (1923). >tlenrinsky.G.. Somak PapperdLln., 45,421-8 (1942). Shsffer,P. A., and Somopyi. M.. J . Bid. Ckem..100, 695 (1933). Somopui. M., Ibid.. 75, 3 3 4 3 (1927). Virtanen, A. I.. and Puikki. L.,J . Am. Chem. Sac., SO. 3138
1,1928).
Figure
6. Wortpkal
Balance and
Jacketed Container
I n the tests, the bob is weighed in sir,in ireshly boiled a'ater, and in the solution that is to he analyzed. The loss in weight of the hob in the solution divided bv the loss in weieht io water gives the specific gravity. Because oi a surface ten& effect on the supporting wire the balance works less smoothly and a less reproducible rest point is obtained when wster is used than when alcohol solutions &re used. T o overcome this difficulty with wster and very dilute alcohol solutions, 1 ml. of a 0.8% solution of a wetting agent. Naeconol NR, is added to the water used for standardization and to the beer distillate boiore final adjustment of the volume. The eNmt of the Nacconol X R on the density oi the alcohol solution is neglected in the calculations, since i t is added in the same concentration to both the unknown solution and the water used for standardization. PROCEDURE.Dislilhlion. A 100-mi. sample of beer is pipetted into 8 500-ml. round-bottomed flask, neutralized using a Spot plate and bromothymol blile indicator, and distilled into a 50. mi. volumetric flask. After about 48 ml. have distilled, the distillation is interrupted and 1.00 ml. of 0.8% Naeeonol NR is added. The volume is then adjusted to the mark. The volumetric f i s k containing the distillate is thermostated at 20" C. DeDetenninalia. The apparatus is standardized against water beiore each day's operat.ions by weighing the hob in freshly boiled distilled water to which ta wettin agent has been added 1 n the w n e proportions as in the beer &stillata The container IS alvays filled to the same level, 80 that the same amount of liquid IS always displaced by the wire supporting the bob. T o initiate B gentle swing of the balance pan on release, a rest point is chosen about 6 mm. ofi center. The determination oi the weight of the bob in the unknown solution is carried out in the same manner. Calmculotias. The specific gravity may be calculated by the following formula:
Yn air
P B ~ S E N before T E ~ the Division of Celluiose Che-try at the 108th Meetin; of the AYERTCAN C a e w r c ~Lioc~nn. ~ New York, N.Y. Bvlsd on ntudiee 01 the U. E. For& Prodvots Irhorstory io cooper8tion with the Offiea of Production Ruresroh and Development of tba War Production Board.
mpgingr Funnel MILTON ORCHIN Conbal Experiment Station, Bureau
of Minor, Pitisburgh, Pa.
HE dropwise addition of compounds to stirred solutions is one of the most common synthetic organic chemistry operations. The funnel shown in the sketch has been iaund very useful in such operations. The funnel incorporates the leakproof stopcock designed b y Newman with d l the advantaps pointed outhyhim (I). Thepressureequslizer feature permits exclusion of the almosplicre and minimizes the attention which the 0perst.m must give to maintain the desired addi-. tion rate. The off-center designoitheiunnelpermitsitto be mounted in B three-necked Hask without interfering with the mercury s e d generally contained in the middle neck. The vertical pasition of the stopcock emure8 that i t wiU not be dislodged by the vibration due to stirring.
i i water
The comntration of the slcohol in the beer in terms of rams per 100 m!. is determined by reierenee to a table showing t%e relationship between specific gravity and alcohol concentration. Since the eoncentration in the distillate is double that in the beer, the value obtained must be divided by 2. T o make routine calculations more rapid, the value of the weight of the bob in alcohol solutions minus the weight of the bob in water m s y be plotted &s a function of the alcohol eoncentrstion in the beer to ahioh it correspmds. I n thls a'ay calculations arereduced toseimplesubtraction sndreference tosgraph.
LITERANRE W E D
(1) Newman. IND. ENO.,Camu. A N A L . E D . . 1 4 , 902 (1942).
Figure 1.
Modified Droppins FLtd
P U B L ~ ~ by B ~parmiaaion D of the DLector..Burasu of Mi-. U. 8. Department of the InUriw.
