July, 1918
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 CHEMISTRY
t o t h e other side of t h e test t u b e contains concentrated sulfuric acid or water, and is there primarily for noting t h e inflow of air into t h e system. It also serves for detecting any leaks in t h e line of connection. All rubber connections are wired, and t h e tips of the glass tubes are not broken until all connections have been made. Before breaking t h e capillary tips, t h e intermediate system is placed under a slight vacuum. The tips are then broken and b y adjusting t h e ?topcocks of t h e evacuated ionization chamber t h e flow of air through t h e chain is regulated. Heat is now gently applied until t h e mass is molten, after which it is boiled for about j min. Sometimes i t is a little difficult t o get good boiling a t this stage, b u t I find where a n equal mixture of t h e fused bisulfate a n d crystals is used, t h a t this difficulty seldom appears. The emanation is swept into t h e chamber by a slow, steady current of air which is maintained during heating until atmospheric pressure is nearly attained in t h e chamber.
FIG. I1
Readings of t h e rate of discharge are made 3 hrs. after t h e introduction of t h e gas, t h e same as in t h e other methods. R E S U L T S A S D DISCUSSION
The results obtained are summarized in t h e following table. The values represent duplicate determinations for t h c most part, b u t some of t h e m are triplicate. The values in t h e table represent grams of radium per gram of material X IO-^. W t . of Material Sample Carnotite No. 1 . . . . . 1,OO Carnotite No. 2 . , . . . 1.00 0.50 Concentrate.. . . . . . . Tailings.. . . . . . . . . . , 3.00 0.05 First S u l f a t e . .. . . . , . 2.00 By-products. . . . . . . .
TABLEI Refined Sulfate 5.15 10.60 29.90
0.90 676.00 1.26
527
method has in this operation over t h e solution method: ( a ) I t is not necessary t o t a k e into consideration t h e “emanating power” of t h e pitchblende in t h e case of t h e bisulfate method, while it is in t h e case of t h e solution method; ( b ) The same carefully weighed samples of pitchblende may be used for several standardizations b y resealing t h e bisulfate melt after t h e emanation has been driven off and collected for standardization. 11-Besides simplicity of operation, t h e bisulfate method is by far t h e most rapid procedure. Not only is t h e actual time required for the final separation of t h e emanation shorter t h a n in t h e other procedurc, b u t t h e time in work expended in preparing a sample and getting it sealed u p is reduced t o a few minutes. 111-The chances for loss due t o manipulation are reduced t o one operation, when t h e material is transferred t o t h e test tube. I n both of t h e other methods great care must be exercised in avoiding losses when fusions are in progress. Instead of one, two t o three transfers of materials occur in t h e other methods. IV-The cost of the operation is reduced. If one is careful t h e test tubes may be used for several determinations. I n t h e refined sulfate method t h e small platinum boats, costing a t least a dollar each are not good for more t h a n 5 t o 6 determinations. The use of larger platinum vessels is essential in t h e other methods, while in t h e bisulfate method all fusions are made in hard glass test tubes. V-After t h e final separation of emanation b y t h e bisulfate method, t h e material remains and is ready for another determination in case a n accident occurs. When t h e material under examination contains thorium, then t h e gas cannot be transferred directly t o t h e electroscope during fusion, b u t must be collected in a gas burette t o allow t h e decay of thorium emanation. 1 wish t o thank Mr. J . C. Simpkins, whoassistedrne a t t h e outset in this work, and Dr. H . Schlundt for his helpful suggestions. CHEXICALPRODUCTS COMPANY DENVER,COLORADO
A RAPID PRESSURE METHOD FOR THE DETERMINATION O F CARBON DIOXIDE I N CARBONATES By W. H. CHAPIN
Mixed Carbonate Bisulfate 5.18 5.22 10.00 10.40 30.00 29.40 0.94 1.00 680.00 678.00 1 ,24 1.27
The good agreement in t h e values shows t h a t from t h e standpoint of accuracy in radium determination, no one method has any advantage for t h e classes of materials examined. The bisulfate method, however, presents some advantages which deserve recognition. I-It has been established t h a t t h e bisulfate method m a y be used in liberating t h e emanation from samples of pitchblende, whose radium content is known, used in t h e standardization of electroscopes. There are two advantages worthy of mention which the bisulfate
Received October 3, 1917
By use of the apparatus sketched below carbon dioxide may be very quickly determined in any carbonate which is soluble in cold hydrochloric acid. The accuracy of t h e method is equal t o t h a t attainable with the absorption method, except possibly when t h e latter is in t h e hands of a very skilled manipulator who has had long practice with the method. The principle is very simple: The carbonate is allowed t o dissolve in dilute HC1 contained in a flask of known volume t o which is attached a small mercury manometer. The change in pressure is read off, and b y a simple calculation t h e weight and percentage of Con are obtained. The necessary details are given in t h e procedure.
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY APPARATUS
The flask is made from a 600 cc. distilling flask b y cutting off the side tube and sealing on t h e manometer tube in its place. T h e latter should have a bore of 5 mm. If too small, t h e capillary effect will interfere with accurate reading, and if too large t h e movement of t h e mercury changes t h e volume of t h e apparatus too much. Attached t o t h e manometer tube is a sliding scale of celluloid 1 5 cm. long and graduated in millimeters. This scale is made from a 1 5 cm. (6 in.) ruler b y cutting out one side as seen in t h e sketch. It is held in place by means of small metal clips which may be slipped out of t h e way when reading. By use of a small lens it is possible t o read t h e position of t h e mercury t o ' / 5 mm. The inside of t h e manometer tube and t h e mercury used in it must be clean and dry or no accurate readings can be expected.
The capsule used for weighing out the sample is suspended by a thread as seen, t h e latter being caught and held in t h e stopcock until i t is desired t o drop t h e sample into the acid. This capsule may be made of copper or any metal not displacing hydrogen from the acid. The stopper should be of rubber, smooth and close fitting. I t s tightness may always be insured b y wetting slightly a t t h e moment of inserting. It should be adjusted t o a mark on t h e neck of t h e flask. To keep t h e temperature of t h e apparatus constant a n d t o make it easy t o determine, t h e bulb of the flask is kept immersed in water at room temperature. The thermometer used in reading t h e temperature is kept standing in this water.
Vol.
IO,
No. 7
Before using t h e apparatus, its capacity is determined b y filling with water from t h e bottom of t h e near a r m of t h e manometer t o t h e stopcock, and weighing. TO prevent t h e water going too far in t h e manometer tube a rubber connector is placed over t h e open end and then closed b y means of a pinchcock. If this is opened slightly after t h e flask is filled t h e water may be adjusted t o any position. PROCEDURE
First set u p t h e apparatus as seen in t h e sketch, surrounding t h e bulb with water a t room temperature. Fill t h e flask with carbon dioxide from a generator or pressure cylinder, and then run in by means of a pipette I O cc. of 3 N HC1 which has also been saturated with carbon dioxide.' Weigh out a sample of t h e powdered carbonate into t h e capsule (0.7 g. where t h e COz content is about 20 per cent, and 0.4 g. where i t is as high as 40 per cent). Suspend t h e loaded capsule as seen in t h e sketch, taking care t o moisten t h e stopper well and t o press i t down t o t h e mark. This may cause a slight compression of t h e gas in t h e flask and a consequent rise in t h e mercury, but t h e effect may be corrected b y holding t h e end of t h e thread a n d opening t h e stopcock for a moment while gently tapping t h e manometer tube. When all is ready place a finger over t h e end of t h e stopcock tube, taking care n o t t o catch t h e thread, and t h e n open the cock SO as t o let t h e capsule drop. After, this immediately close t h e cock again. The carbonate usually dissolves within a minute, b u t i t is always best t o watch t h e manometer for about 5 min. for further rise, tapping gently in t h e meantime. Finally, when t h e reaction is complete, adjust t h e scale so t h a t t h e lower end corresponds with t h e meniscus in t h e near a r m of t h e tube and then read off t h e height of t h e column in t h e other arm. Great care must be taken t o get exact adjustment and t o avoid parallax. Read t o centimeters and tenths and estimate t o hundredths. Also take t h e temperature accurately . We now have t h e volume of t h e COz a t room temperature, Vt (vol. of flask minus IO cc. occupied b y acid). We also have t h e pressure P of t h e COz (as read on t h e manometer), Finally, we have t h e temperature t . We can get t h e weight of t h e COz by calculating down t o standard conditions and multiplying into t h e weight of I cc. of COz under standard conditions (c.001965 g.). We then have:
Since t h e factors V t , 2 7 3 , 0.00196 j and 760 are always t h e same, we may work out t h e value of t h e fraction 1 If the acid is not first saturated with C O I a part of the gas evolved during the reaction will remain in solution. If the flask i s not first filled with COz a part of the gas dissolved in the HC1 will a t first be given off, and later during the determination, when the pressure of the COz rises, gas will again go into solution. Where the pressure of the Cot in the flask is one whole atmosphere at the start, no gas will be given offfrom the acid, and since the change in pressure during the determination will be comparatively slight, very little will then go into solution. It is best to keep the stock of HC1 in a gas wash bottle connected with a Kipp generator, where COz may a t any time be forced through it. The tube through which the COz is led into the apparatus when filling with this gas is attached to the wash bottle. Thus every time the apparatus is filled just that much COz passes through the acid.
July, 1918
T H E JOCR,VAL OF I N D C S T R I A L A N D ENGI-VEERING C H E M I S T R Y
Vr -
X 273 X
P R E P A R A T I O S O F SAMPLE
0.001965
760 a n d call this t h e constant for the apparatus, K . We then have : KP W t . of coz = 273 t T h e percentage of COZin t h e carbonate t h e n follows, thus IOO K P Percentage of COz = (273 t ) X Wt. of sample‘ By use of logarithms t h e necessary calculation may be made in less t h a n 2 min. The total time consumed in making a determination, including t h e weighing and calculation, need not be over I j min. After completing a determination t h e capsule may be lifted out of t h e apparatus b y means of a wire hook, a n d t h e spent acid may be drawn out with a pipette. T h e apparatus is then ready for the next determination without even refilling with COZ. ~
+
+
Calcite Per cent COz 43.53 43.67 43.40 43.52
Av., 43.51 By ignition 43.59
24.71 24.34 24.67 24.36 24.59
NanCOa aq. Per cent COz 34.74 34.40
By absorption method
-
34.59 34.30
Av. 24.53 B y absorption method 24.47(a)
( a ) Average of 100 determinations varying from 24.1 per cent to 24.8
per cent. SEVERANCE CHEMICAL LABORATORY OBERLINCOLLEGE, OBERLIN,OHIO
A PROXIMATE ANALYSIS OF THE SEED OF THE COMMON PIGWEED, AMARANTHUS RETROFLEXUS L By EVERHART P. HARDINCAND WALTERA. EOGE Received August 3, 1917
I t was thought b y t h e authors of this paper t h a t t h e partially carbonized bracts of t h e seeds of this common plant might make a good filtering medium €or decolorizing sugar and other colored solutions. This suggested other possible uses of t h e seeds which led t o their proximate analysis. D E S C R I P T I O N O F PL.4NT’
This variety of pigweed is commonly called “red root,” “rough pigweed,” “green amaranthus” and “Chinaman’s greens.” I t is a n annual weed which grows from a well-formed a n d fairly deep-rooted t a p root. The root is generally red. The plant grows from I t o 3 f t . high and is branched, t h e branches coming obliquely from t h e stem. T h e stem and leaves are rough. T h e plant flowers fron; July t o September. These flowers are very inconspicuous, appearing in t h e angle formed by t h e stem and leaf stalk. The seeds are oval, black and shiny, a n d ripen during August, or before. The weed occurs in all parts of t h e State of Minnesota a n d thrives in all kinds of soil, b u t prefers a rich loam. It is common in gardens and waste places and does most injury b y crowding out crop plants. 1
p. 37.
The seeds were stripped from plants growing in Waseca County in t h e southern p a r t of Minnesota. They were cleaned b y removing foreign matter and chaff (bracts). The separation and removal of t h e bracts was difficult and tedious. Approximately 7 5 per cent of t h e seeds were black a n d fully matured, t h e rest were red, showing varying degrees of maturity. The sample was rapidly ground t o 20-mesh size and t h e moisture determined on a portion of this size t o represent total moisture in t h e seeds. The rest was air-dried for 7 days and then ground t o a 7a-mesh size. Moisture and all other determinations were made on this size sample. AKALYSIS
AND 7 2-MESH S A M P L E S - O ~ ~ gram samples were dried in an electric drying oven a t exactly 100’ C. Preliminary tests showed t h a t 14 and 4 hrs., respectively, were required t o bring the 20- and 72-mesh samples t o constant weight. MOISTURE
IN
20-
-20-Mesh-
RESULTS Argillaceous Limestone Per cent COz
529
Minnesota Agricultural Experiment Station, Bull. 129, March 1913,
I
....
I1
Moisture content, grams., 0.1127 0 . 1 1 2 9 Average percentage of moisture 11.28
-72-Mesh-
I
I1
I11
0.0860
0.0860 8.60
0.0860
AsH-Ash was determined on one-gram samples in an electric muffle a t a temperature of 620’ C. I
....................... 0.0445 ......... .....
Ash content in grams., Average percentage of a s h . .
I1
I11
0.0448 4.46
0.0446
It was very difficult t o burn t h e substance completely t o a n ash- over a Bunsen burner. D E T E R M I N A T I O K O F O I L ( E T H E R EXTRACT)-AbOUt one-gram portions of t h e material, dried respectively t o constant weight in a n air oven a n d in a vacuum sulfuric acid desiccator, were extracted in Soxhlet extractors with anhydrous, alcohol-free ethyl ether t o completion, which required 16 hrs. I Oven dried, grams o i l . . . . . . . . . . . . . . . . . 0.0798 Desiccator dried, grams oil. . . . . . . 0.0814 Oven dried, average percentage of o i l . . . Desiccator dried, average percentage of oil
I1
I11
IV
0.0793 0.0788
0.0788 0.0801
0.0791
....
7.92 8.46
The dried oil dissolved in cold sulfuric ether, b u t not in cold petroleum ether. PRoTEIK-Protein was determined b y Gunning’s modification of Kjeldahl’s method, using one-gram samples a n d t h e nitrogen conversion factor 6.2 j . I Proteincontent, grams.. . . . . . . . . . . . . . . . 0 . 1 8 8 0 Average percentage of protein. , , . , . . ,
. .
sT A R cH
DE T E R MIN A TI
I1
I11
0.1873 0 . 1 8 6 7 19.13
o N (ACI D c o N V E R SI o N
IV 0.1880
ME T H OD)
-Three-gram samples were used. The usual acid conversion1 of starch into dextrose was made and t h e amount of dextrose determined b y t h e MunsonWalker method.z The seeds occupied a volume of 2.10 cc., for which allowance was made. Aliquot parts of t h e solution equivalent t o 0.30 g. of substance were used in t h e reductions a n d t h e starch conversion factor of 0.90 was used. The following amounts of reduced cuprous oxide and t h e corresponding weights of dextrose and starch were found. ISachse, Chem. Zenlr., 1877, 732; Bureau of Chemistry, U. S . Dept. of Agriculture, Bull. 107. 2 Browne, J . A m . Chem. Soc., 1906, 439.
