A N D ENGINEERING CIIEMISTRY
34 ,357 0 . 6 3 8 E. ammonia is destroyed b y 6.699 z. sodium hypobromite Z N ~ O H nr? m ~ i o .manr IM) 80 1 hO 119 2 s EC. 1,romi,,e = 7 9 . 5 L. bromine , 3 0 0 C C . soli,iior, conta1iis 1 7 . i il. hyUohromifc tappron.)
+
-.+
+
+
There shoulil be a large excess of hypobromite. quirud for safcty.
This
is IC-
Soap should never be used in cleaniny any piece of apparatus used in this test. We found that beakers which 1r:id been washed with soap and were later used as receivers threw the results very much too high even after being rinsed 8 or I O times.
555
siderable degree of accuracy is required in the determinations made in this laboratory t o ensure compliance with the regulations. At first the method used was a slight variation of that published by Holde and Winterfeld,' as modified by Wolf.* As admitted by these authors, the results are below the truth. Holde and Winterfeld apply a correction of + 0 . 3 per cent. I t is obviously impossible t o obtain satisfaction from a method which calls for a correction equal t o 60 per cent of the probable total. Having satisfied ourscloes that the method is suhject t o errors arising both from the principles on which it rests and from its manipulative details, we have designed another means of measurcment which is both more accurate and more rapid. This is now adopted as the standard method for its purpose by the Inland Revenue Department of Canada. DESCRIPTIOX
OF
THE
1IOLDE-WINTERFELD-WOLFX
METHOD
To loo cc. of the alcohol-benzene solution, water is added till the sp. gr. is brought t o 0.96. This mixture is distilled, the first I O cc. (Hnlde-Winterfeld) or 20 cc. (Wolff) of distillate being collected and transferred t o a graduated vessel. The distillate is diluted with 20 cc. water (Holde-Winterfeld) or 80 cc. saturated brine (Wolff). The volume of benzene which separates is read, giving the percentage direct. I t usually takcs 2 t o 3 hrs. for the benzene to collect sufficiently for the reading to be made. The benzene layer is never clear and the accurate determination of its limits is usually very difficult. RESULTS B Y THE HOLDE-WINTERFELD-WOLFF METIIOD
Fro.
APPARATUS USINO G n o u ~ oC L A S S C u ~ ~ s c r r o.AND ~s S i o ~ ~ r TO r ~Ds K T ~ ~ R XTXB Z NINPLUIBNCB E OF Ruensa
J-SPBCLAL
The apparatus now used in this laboratory is indicated in Fig. 2 . During the course of our investigation the question arose as t o the influence of the rubber stoppers and connections. I n order t o determine this an apparatus was constructed in which all joints and stoppers were ground glass. The determinations made on this apparatus are indicated in Table V. Our conclusion is that the rubber is not objectionable, provided a good grade is used. AKTNRL~aoarronv d a r r a ExP,.osi"ns C O M P A N Y AWN*. INMAWA
The determinations tabulated below were made upon solutions of benzene in alcohol ( 9 5 per cent by volume) prepared with great care to known strengths. I n all cases the first portion of distillate taken was I O cc. I n some cases a second portion of the next I O cc. or 20 cc. was eoilected and examined separately. The figures show, however, t h a t this precaution is nnavailing, as the amount of benzene so collected is too small for detection by this method. Volmnc of Dirtillate Collecfuf First S s o n d RunR"n1Sn~r.n i n ~ s n m y s NO. Cc. Cc. 2I
10 "
in
10 10
I0
..
0.5 1.2
0.0
10
20
1.3
0.0
10 10
3
.I .5 6 7 3
T a a ~ sI Volume of Hazetie Found First Second RunRunnings ningr Cc. CE. o.n 0.0
10
10
0.0 0.3
0.4
0.0 0.0 0.0
...
Correction medc by addiiir f0.3
Tola1 H&zeneFoud Percent lincorPer Cent rectrd Corrected' 0.0 0.0 0.3
Benzene Aefually PreSenf Per cent
0.3
0.2
0.3
0.2
0.4
0.6 0.7
O.i 1.2 1.3
0.8 1.5 1.6
0.8 1.6 1.6
according
10
0.4
0.8
lluldr and Winter-
idd.
DETERMINATION OF SMALL AMOUNTS OF BENZENE IN ETHYL ALCOHOL B y F. W . BARINDTON A N D ALPLIIDTINGLB Received Ociaber 28, !Vi8
For certain war purposes, and under restrictions, the Inland Revenue Department of Canacla allows alcohol t o be denatured by the addition of benzene. Since o. j per cent of benzene is allowed t o suffice, a con-
It is evident that without the use of a correction, the figures obtained are so inaccurate as t o be useless, and thnt the "correction" is only correct for cases where the benzene is present t o the extent of nearly I per cent or more. For our purposes such a method is useless.
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
556
T o I O O cc. of the solution t o be tested, 2 0 0 cc. of water are added. No matter how strong the alcohol this is enough water t o bring the sp. gr. above 0 . 9 6 , a n d a moderate excess of water is no disadvantage. T h e mixture is distilled a n d t h e first 2 0 cc. of t h e distillate is collected in a suitable graduated vessel. We have found a straight 50 cc. Eggertz tube, divided into tenths of a cubic centimeter, very suitable. It must be provided with a close-fitting straightsided rubber stopper for insertion when t h e distillation is completed. A 50 cc. burette may be substituted for the Eggertz t u b e if allowance is made for t h e volume of t h e undergraduated portion immediately above t h e stopcock. Some such straightsided vessel has great advantages over one in t h e form of a flask, a n d graduated cylinders with small enough subdivisions cannot easily be obtained. Should i t be suspected, from the appearance of the mixture after dilution, t h a t the benzene present exceeds 0 . 7 5 per cent, it is a wise precaution t o collect a further I O cc. of distillate (making 30 cc. in all) in a separate vessel. This second running should be treated like the first 2 0 cc. a n d any benzene found i n it should be added when t h e percentage is being calculated. The rate of distillation should be about I cc. per min., and should not be allowed t o exceed 1.5 cc. per min. T o the distillate t h u s obtained is added 1 5 cc. of potassium dichromate solution ( l / e saturated) followed by 2 cc. of hydrochloric acid (sp. gr. 1.2). After mixing well, t h e closely stoppered tube is allowed t o stand till an olive-green color develops. Fifteen minutes generally suffices. By careful measurement from a pipette, I O cc. of petroleum ether are next added t o t h e contents of the tube. T h e mixture is thoroughly agitated, then allowed t o separate into two layers, and t h e volume of the upper layer read. This volume less I O cc. gives t h e percentage of benzene present in t h e sample. I n the table below will be found the results obtained by this method on t h e same mixtures employed for our determinations by t h e Holde-Winterfeld- Wolff method. TABLS I1 Volume of Benzene Found First Second Runnings Runnings cc. cc.
Total Benzene Found Per cent 0.2 0.2
11 12 13 14
20 20 20 20
.. .. .. 10
0.7 0.7 1.4 1.5
...
... ...
0.1
0.4 0.4 0.7 0.7 1.4 1.6
THE PROXIMATE ANALYSIS OF WOOD By W. H. DORE Received October 21, 1918
0.2
The above table shows only three divergences between t h e benzene found a n d t h a t known t o be present. I n every case this is due t o our having neglected t h e precaution we recommend of collecting a second portion of distillate. Such errors are small a n d only occur where t h e percentage of benzene is relatively high. Certain experiments which we have made, t h e details of which need not be given, show t h a t t h e presence of a large amount of acetone in t h e distillate would increase the apparent ,amount of benzene.
No. 6
ANACYTICAL LABORATORY DEPARTMENT OF CUSTOMS AND INLANDREVENUE OTTAWA, CANADA
Benzene Actually Present Per cent 0.2 0.4 0.4 0.8 0.8 1.6 1.6
11,
Pyridine would give a similar result, but its interference can be quite overcome by increasing t o 3 cc. t h e amount of hydrochloric acid added in the oxidation stage of t h e determination. I t may be noted t h a t determinations can be made more rapidly by t h e new method t h a n b y the old, t h e accuracy being a t t h e same time increased, while t h e use of a n arbitrary correction is avoided.
DESCRIPTION O F CANADIAN INLAND R E V E N U E METHOD
Volume of Distillate Collected First Second EXPT. Runnings Runnings No. Cc. cc.
Vol.
’
This paper is a preliminary report on a s t u d y of t h e chemistry of certain California woods from t h e standpoint of their chemical utilization. As t h e first step in this investigation a complete proximate analysis of these woods has been undertaken and a consideration of the analytical methods employed and results obtained is herewith presented. There have been numerous contributions t o the literat u r e of wood chemistry in recent years. Most of these have been of a rather scattering nature, b u t several investigators have undertaken t h e systematic investigation of t h e chemistry of particular woods. While much information as t o constituents of wood a n d methods of procedure has resulted from these studies, t h e d a t a now available has the defect of not being summative. Examples of complete analyses of woods are practically absent from t h e literature, if we except a few a t t e m p t s in which t h e undetermined matter is broadly classified as “non-cellulose material b y difference.” An analysis of a wood in which all of its material is accounted for appears t o have advantages over one t h a t gives a number of constants of t h e wood without expressing their summative value, from both theoretical and practical standpoints. Our knowledge of t h e chemistry of wood cannot approach completeness as long as there is a large gap of undetermined constituents. Neither can a wood be completely evaluated commercially until all constituents of possible economic importance have been determined. I n view of t h e exceedingly complex nature of wood a n d t h e meagerness of our knowledge of wood chemis: try, a complete analysis can mean nothing more t h a n a separation of t h e wood substance into groups of compounds. It appears t o be quite practicable, however, t o effect a grouping of wood constituents on t h e basis of chemical similarity t h a t will have definite theoretical a n d commercial significance a n d serve as a starting point for further study. T h e structural substance common t o all woods is ligno-cellulose, a material in which two constituents (cellulose a n d lignin) are found a n d which are believed by most investigators t o be chemically combined. Somewhat allied t o cellulose are t h e hemi-celluloses, distinguished from t r u e cellulose by a feebler resistance t o t h e action of chemical reagents. These substances are found t o a greater or less degree in all
