INDUSTRIAL AND ENGINEERING CHEMISTRY
July 15, 1929
SAMPLB49-A
SAMPLE50-A
%
%
104.8 165.9
91.3 151.7
Sulfur by regular bomb method Sulfur by modified bomb method
This experiment shows that the lamp method does not give all the sulfur where mercaptans are present. It also shows, in this particular instance a t any rate, that a large proportion of the sulfur was converted in the bomb to substances having soluble barium compounds, probably sulfonic acids. Whether or not this is due to the mercaptans we have no evidence as yet. -WINKLBRA B Av.
%
%
Sulfur by regular 1.18 1.26 bomb method Additional sulfur 0.16 0.20 by refluxing Total sulfur 1.34 1.46 Sulfur recovered by regular bomb 88 0 86 3 method Sulfur b y lamp 120 103 method Total sulfur recovered by lamp 85 7 73 6 method
%
HOWARD -SMACKOVER- GLASSCOCK A B Av. A B Av.
%
%
%
%
%
%
1 . 2 2 1 . 6 4 1 . 7 5 1.695 1.67 1.72 1.695
.
0 . 1 8 0 . 2 1 0 . 2 2 0 . 2 1 5 Lost 0 . 2 8 . . 1.40 1.85 1.97 1.91 . 2.00 2.00
.
87 1
88 7 88 8 88 7
83 5 86 0 84 8
1 12
112 132 122
1
80 0
58 6 69 1 63 9
65 0 65 0 65 0
;?)
130 130
EXPERIMENT XI-Three samples of crude oil-Winkler, Smackover heavy, and Howard Glasscock-were analyzed by the usual bomb method and the filtrates were refluxed with hydrochloric acid and the additional barium sulfate
169
determined as in method (5) under Experiment VIII-B. These oils were also diluted with a kerosene containing 0.041 per cent sulfur (lamp method) and tested for tots1 sulfur by the lamp method. The results in opposite column were obtained. Conclusions
1-In the usual bomb method for sulfur in petroleum oils part of the sulfur is in most cases oxidized to sulfonic acid or similar substances. The barium salts of the sulfonic acids are soluble in water and consequently the determination gives low results. 2-The sulfur as sulfonic acid may be recovered by refluxing the evaporated filtrate from the barium sulfate precipitation with concentrated hydrochloric acid. This converts the sulfonic acid to sulfuric acid. 3-Both the usual bomb method and the lamp method give low results for oils containing mercaptans. Apparently the mercaptans are largely oxidized to sulfonic acid in the bomb. When burned in the lamp they form some other compound than SOz or SO3 and are lost. 4-It is not possible to determine sulfur on heavy crudes with the lamp method by diluting with kerosene and burning the mixture. On very heavy crudes the recovery of sulfur by this procedure may be as low as 65 per cent.
An Improved Volumenometer' Alfred W. Francis and Edward P. Oxnard ARTHURD. LITTLE, INC., CAMBRIDGE, MASS.
T IS sometimes necessary to determine the true volume or density of a powder or irregular solid which is soluble, porous, or otherwise unsuited for liquid displacement methods. Various forms of volumenometers have been proposed ( I to 4),* but they have been found unsuitable or of insufficient accuracy for the purpose. Accordingly, the writers have devised certain improvements which make the apparatus very simple and satisfactory. A volumenometer determines volumes by air displacement and depends upon Boyle's law. The volume of a bulb is calculated from observations of two air pressures-one when a certain amount of air is contained in the bulb alone, and one when the Sam-e amount of air is expanded to fill the bulb and an additional known volume. The operation is repeated with the sample in the bulb. The difference in calculated volumes gives the true volume of the sample. The known volume has been measured commonly by means of two marks on a cylindrical tube. It is more accurate to use a pipet bulb with calibrations both above and below the bulb. A serious defect in most forms of volumenonieter is the difficulty of making a sample bulb with a wide mouth so as to introduce large samples, and yet be capable of being closed airtight to a constant volume, which precludes the use of soft gaskets.
I
Description of Apparatus
The apparatus is illustrated in the figure. The sample is weighed into the flat-bottom bulb, which is similar to a weighing bottle but of Pyrex glass and heavier in construc1
Received April 18, 1929.
* Italic numbers in parenthesis refer t o literature cited at end of article.
tion. The neck is provided with a steel collar with screws which clamp down the ground-glass cover under a rubber or leather washer, thus holding the pressure. The ground-glass joint is lubricated with lanolin before closing. To the cover is sealed a short capillary glass tube, which is connected to another capillary &be by means of a short piece of rubber pressure tubing. The pipet bulb is made from a pipet upon which a second graduation is etched below the bulb and calibrated, preferably with mercury, before breaki n g off i t s t i p . For greatest accuracy the v o l u m e of the pipet bulb should be slightly s m a l l e r than that of the sample bulb. This pipet bulb is supported by a clamp (not shown in the figure). Themanometer, preferably about 2 meters long, is provided with t w o m e t e r rods, the lower one i n v e r t e d . The zero marks of the meter rods are set opposite the pipet graduations. The exact posi-
I
b
ANALYTICAL EDITION
170
tion, which corrects for any error due to capillarity, is found by disconnecting the sample bulb, setting the mercury at a pipet calibration, and using the mercury level in the other tube as a zero mark. The leveling bulb, with a capacity of I50 to 200 cc., is supported by either of tm7o split rings as shown. In the lower position the mercury levels are at B-B-B and the reading of pressure below the barometer, PI, is made when the mercury in the pipet is a t the lower graduation. The leveling bulb is then raised to the other ring, so placed that the upper graduation in the pipet is reached and the levels are at A-A-A. The pressure above the barometer, Pz, is read. The readings are repeated until a t least three checks within 1 mm. are obtained on both upper and lower readings, since at first there is usually a slight creeping of the levels. The use of two rings facilitates ’ the finding of the proper positions. Frequently the ground-glass cover of the sample bulb becomes stuck so tightly that it cannot be pulled out. I n mch cases it can be removed by connecting air or water pressure to the tube. Calculation of Volume
Volume of pipet bulb Volume of sample bulb (empty) Weight of sample Barometer UPPERREADINGS (Ps) 266.7 267.3 267.6 267.3 Mean 2 6 7 . 2
96.04 cc. 123.65 cc. 2 3 . 8 grams 768 mm. LOWERREADINGS (PI) 224.0 224.0 223.0 224.0 223.8
Then, applying Equation 2,
.
The true volume of the sample is therefore 123.68 CC. - 106.43 CC. = 17.22 CC. and from this volume and the weight of the sample the true 23.8 density is -17.22 It might be interesting to note that the apparent density as calculated from linear measurements is 0.606. This indicates 56 per cent of voids.
The method was found equally applicable to wet samples provided a correction was applied for vapor pressure of water a t the surrounding room temperature. For wet samples the formula becomes
The calculation is expressed most simply by the equation: Difference in volume - small volume Difference in pressure small pressure
VOl. 1, K O . 3
v=
(1)
B-PI- W p1 P2
8’
+
(3)
where W is the vapor pressure of water. For wet soluble subin which the difference in volume is the calibrated volume of stances this correction should be replaced by the vapor presthe pipet bulb, V’; the difference in pressure is the sum of sure of the saturated solution. The apparatus has been in use for six months and has the two readings on the meter rods, P I Pp; the small pressure is the barometer reading, B, minus the lower reading, P I ; given satisfactory results with such materials as soap, leather, and the small volume is the gas volume, V , in the sample and various powders. It is to be noted that pockets of air within a sample, even if they are enclosed completely, are bulb including the capillary tube. Therefore, compressible. and so are not included in the calculated volume, B - PI V _ _V’ =or V = (2) unless the solid material is rigid. Pi Pz B - Pi pi pz By determining the sample bulb volume empty and subLiterature Cited tracting the volume when it contains the sample the true Chwolson, “Lehrbuch der Physik,” Vol. I, p. 303 (1918). volume of the sample is obtained. With sufficient care (1) (2) Dobrochotow, Z. Hauptanstall Masse Gewichte, 8, 91 (1907). volumes can be estimated with an accuracy of 0.2 or 0.3 cc. (3) Lo Surdo, Nuovo cimento, [ 5 ] 12, 41 (1906). The results obtained on a sample of leather are as follows: (4) Zeleny and McKeehan, Phys. Reo., 30, 189 (1910).
+
+
+
Bottle for Accurate Weighing of Volatile Liquid Mixtures‘ 2. Blaszkowska POLYTECHNIC HIGH SCHOOL, WARSAW, POLAND
0 WEIGH several liquid components of a mixture in one container is usually a long, difficult task. When weighing one of the liquids following the first it is easy to pour too much, necessitating a new calculation and the addition of new portions of the liquid already weighed. There are still more difficulties when mixing easily volatile liquids, for weighing bottles with capillary tubes and capillary pipets are then necessary and the time of weighing is still longer. During work on esterification, the author designed the apparatus shown in the accompanying figure, which facilitates and shortens the weighing, and is very accurate. It is especially suitable for weighing easily volatile liquids. The apparatus consists of two containers, A of about 100 cc. capacity and B of about 50 cc. capacity, depending on the amount of the liquid to be weighed, joined by the S-shaped tube, C. The small tube D in container A is closed by means of a rubber tube with a glass stopper or by a glass stopper 1
Received February 28, 1929.
directly. Container B has a wellground glass stopper. The first liquid is weighed into B by pouring it through the inlet K; the side tube D must be closed. The liquid partly fills the container B and part of the bent tube C. The liquid can be added or removed with a pipet through K . After the weighing the opening K is closed and the liquid is poured from B to A by inclining the apparatus. The bent tube C must be wide enough (6 to 8 mm.) to allow the simultaneous passing of the liquid from B to A and of the air from A to B. Each of the other liquids is also weighed in the container B. The first por-
