J a n . , 1919
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
pared in accuracy and reliability t o the original or modified Allen and Bishop method. Fur$her, t h a t the latter method is a n excellent one, easy and simple of manipulation. Many laboratories hitherto unfamiliar with this method have now adopted it, either in its original or modified form, with the result t h a t in future better agreement among laboratories on this determination may be expected. Tables 111, IV, and V give a brief summary of the work for the two previous years. It will be noted in Table V, comparing results of Samples z and 3 with results on the same samples for t h e previous year, t h a t the results on Sample 2 for both years are in close agreement, but in case of Sample 3 , results are considerably lower t h a n those in 1915. The reason for this is t h a t Sample 3 is a sample of Spanish ore, which oxidizes quite rapidly when finely ground, and when samples for 1916 were bottled u p after remixing the large portion, a distinct odor of SOz was observed. CONCLUSIONS
The conclusions arrived a t for the work of previous years seem t o apply equally t o t h a t of the prehent year and are as follows: I-The disagreement by t h e Lunge method is about i n line with past experience. z-The agreement b y t h e Allen a n d Bishop method, either the original or the modified, is much better and in the hands of analysts experiehced with the method yields results in close agreement, closer, in fact, than is the case with most analytical determinations. 3-The Allen and Bishop method is recommended t o all chemists as a n accurate method for determination of sulfur in pyrite. The writer wishes t o thank again all those who have so generously participated in this undertaking for their work and valuable suggestions. It is hoped t h a t all who have taken part feel amply repaid for their efforts and it is believed t h a t in future a better agreement between laboratories for t h e determination of sulfur will be observed.
49
From these tests the offset sample would appear a good match in strength t o the rope stock. But envelopes made from the offset stock proved worthless. An off-hand examination of these two papers with the fingers showed a great difference in the tearing quality as is t o be expected when the difference between their compositions is considered. A Schopper folding tester would, no doubt, have shown a great difference between these papers, but none was at hand. A means was then sought for measuring the tearing quality of paper. The method finally adopted gave the following results on the two samples mentioned: TEARING RESISTANCE
............................... ............................
With grain Across grain..
Rope Stock Grams 240 250
Offset Stock Grams 95 125
The test as now used has many disadvantages, but gives reliable information, particularly when used along with the Mullen tester. A low Mullen test and a high tearing resistance is sometimes a highly desirable condition. The Mullen tester shows the hardness and rigidity, while the tearing resistance shows the fiber strength and the extent of peeling. A wrapping paper t h a t peels when tearing is certainly superior t o one t h a t does not. The effect of humidity variation upon the results obtained with t h e tearing-resistance tester has not yet been worked out. The indications are t h a t these tests are not affected to the same extent as those made on the Schopper folding tester. The details of making the test are as follows: Twelve strips, I in. by z1/2 in., are cut from samples representative of the lot to be tested. Six of them are cut with the long dimension parallel t o the grain of the paper, and six are cut across the grain. These are cut with the scissors, as shown in Fig I . It is easier t o slit the test piece t o about in. from the end of t h e strip and then t o cut off the end AA‘, so t h a t the slit stops in. from the end. A knife slit is not t o be recommended; neither should the tip of the scissors be used a t the end of the slit.
ARMOUR FERTILIZER WORKS GEORQIA ATLANTA,
A‘
A PAPER TEARING-RESISTANCE TESTER By H. N. CASE Received August 9, 1918
-----
T o anyone making a review of the literature on strength tests for paper, t h e subject would appear simple and quite well defined. After making tests on t h e Mullen “pop tester” and the Schopper tensile machine, the writer was therefore surprised t o find t h a t the results often bore no relation to the usefulness of the paper. For example, two papers were t o be compared for use in making “tension envelopes.” The one was a rope Manila and the other a short fibered offset paper. These results were obtained : Weight per ream, 500 - 24 X 35 inches.. Mullen test ............................. Tensile strength on Schopper tester With grain.. ....................... Across grain..
......................
.
..
Rope Stock Lbs. 79
54 Kg. 12.6 6.5
Offset Stock Lbs. 79
sa
Kg. 14.0 7.0
---- - --- -
A FIG.1
The apparatus (Fig. 2 ) is provided with a set of three buckets of different sizes, so t h a t when filled with water a range of weight from 1 5 t o 600 g. can be obtained. One of these buckets is selected according t o the strength of the paper. The test piece is clamped, as shown, a n d t h e water allowed t o run slowly into the bucket until the two parts of t h e piece completely separate. The cock is
50
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
instantly shut off and the bucket with the water and lower clamp weighed. The weight in grams is taken as the tearing-resistance number. It will be noticed in making these tests, t h a t there often is an initial tear when only a small amount of the load is applied. This tearing stops before the final maximum load is reached.
TABLE11-KRAFTS
FROM
sn .. 30 31 32 32 33 33 34 34 34 35 35 36 36 36 37 37 40 40 42 48 50 50 50 51
5.2
FIO.2
If a tearing distance of more than l / 4 in. is used, the peeling effect will have more influence upon the results. Several attempts have been made t o measure the tearing resistance of paper when it is torn for a considerable distance, but the great irregularity in formation and the peeling tendency discourage these methods. Also, no very satisfactory results can be obtained by clamping the slit test piece described above in a Schopper tensile machine and then measuring the load required t o separate the two pieces. The exact width and length of the strip is of little importance, except in the case of very stiff cards, such as postcard stock. The water should not be permitted t o splash into the bucket. I t s exact rate of flow is not important, except t h a t the amount of water allowed t o run into the bucket'after shutting off the cock must not introduce a n error large enough t o be of any significance. Of course, the delivery tube must not drain after t h e cock is shut off. The bucket need fall but a n inch so t h a t there is no danger of any of the water splashing out. TABLBI-MANILAS ~~
Weight per Ream 500-24 X 36') Lbs. 43 50 50 60 60 70 70 80 80 80 86 86 124 125 125 126 200
Mullen Test 17.7 18.8 23.1 28.4 23.0 18.9 61 .O 54.0 54.9 22.0 67.4 74.1 29.2 97.0 87.0 32.0 96.0
~
Tearing Resistance With Across Grain Grain 47 43 41 49 39 46 68 73 39 50 49 47 88 111 250 240 118 92 93 99 133 96 96 148 95 74 196 217 214 226 115 122 444 418
Schopper Tensile Strength With Across Grain Grain 5.1 3.5 6.5 3.2 7.3 5.5 8.7 5.8 7.7 5.0 6.7 5.1 15.5 5.3 12.6 6.5 15.4 5.7 7.4 4.5 20,6 6.5 21.2 5.9 914 6.6 Over 29 22:6 11:s 1116 8.5 Over 29
.,
..
54 55 58 60 60 62 66 68
No.
I
4
Tearing Resistance With Grain Across Grain 34 44 43 50 29 40 63 113 25 48 45 76 28 30 56 73 26 36 34 41 50 52 39 40 31 44 30 68 32 33 45 56 43 57 49 67 57 69 35 32 49 66 45 86 55 66 65 126 49 59 45 81 48 71 45 73 52 58 42 80 62 61 53 62 63 96 73 93 130 209 59 71 101 126 95 180 77 92 80 94 111 128 115 130 50 78 102 124 84 86 128 152 102 124
Mullen Test 13 18 10 11 14 23 21 24 16.5 21 23 24 25 19 16 20 24 21.5 21.5 19 21 23 25 33 19 20 25 24 21 24 21 24 32 34 43 46 48 43 35 37 60 54 38 44 39 68 44
~~
XI,
DIFFERENTLOTSOF PAPER MADS BY SEVERAL Mlrr
Weight per Ream 500-24 X 36' Lbs. 19 19 21 22 23 24 25 26 27 27.5 28 29 30
Vol.
TABLE111-WRAPPERS Weight 500-24 X 36" Tearing Resistance Lbs. Mullen Test With Grain Across Grain 53 42 53 27 65 46 62 12 73 53 59 20 57 63 56 32 73 65 65 32 72 69 103 42 TABLEIV-ENAXELS Weight per ream, lbs. 500-25 X 38 in.. , Rag content, per cent.. Mullen test, lbs.. , Schopper test, kilos With grain.. Across grain.. Tearing resistance, grams With grain.. , , , Across grain.. , , ,
.. . . .. .. . .. .. ... ... .. ........ .. ....
. .... .. ... ...
Low-Grade
Low-Grade
High-Grade
66 None 21
67 3 20
65 50 23
4.7 3.3
5.9 3.0
5.3 3.0
19 23
19 25
27 31
TABLE V-MISCELLANEOUS SAMPLE
Weight Found 1-Enamel.. , 25 38-60 25 X 38-60 2-Enamel.. 1-Draw sheet.. 0.010 in. 2-Draw sheet.. 0.010 in. 3-Draw sheet., o.oio in: 1-Cover stock, 25 X 38-143 2-Cover stock. 25 X 38-145 3-Cover stock. 25 X 38-145 1-Tag stock.. 2-Tag stock,. 3-Tag stock.. 24 X 36-60 1-Envelope.. 24 X 36-60 2-Envelope.. 24 X 36-58 3-Envelope..
.. .. .
...
.... ..
2
Tearing Resistance With Across Mullen Grain Grain Test SERVICE 18 17 Fair 25 10 17 T o o brittle 18 104 68 N o t satisfactory 139 146 70 Satisfactory 151 82 Very satisfactory 180 190 39 Not satisfactory 93 100 140 175 60 Satisfactory 175 72 Very satisfactory 200 670 1.50 Not satisfactory 590 150 Satisfactory 800 820 155 Satisfactory 800 1110 14 Good 41 52 12 Fair 33 83 18 Fair 36 36
The tables above will show the relation of the tearing-resistance number t o other tests. The d a t a is representative of a large amount of routine testing done during the past three years. No attempt was made t o pick out abnormal samples. Discrepancies between t h e Mullen and tearing-resistance numbers are more often found in testing
Jan., 1919
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
51
Manilas t h a n krafts. T h e old “point per pound” should hold somewhat more t h a n this volume so t h a t standard is a fairly reliable one in t h e case of krafts; there may always be a n excess of strong absorption still there are several instances shown in Table I1 where liquid. A piece of capillary tubing, 1.3 mm. inside soft kraft samples have a greater tearing resistance diameter and I O mm. long, is inserted a t E. The outt h a n the Mullen test would indicate. ‘side diameter of t h e tubing used is 7 , 8 . 5 , and 9 . 5 mm. as indicated. If absorption from a smaller ADVANTAGES O F TEARING-RESISTANCE T E S T volume of air is made, a pipette with smaller bulbs A I-The comparative length of the fiber and the peel- and B and a smaller capillary a t E should be used. If ing qualities of the stock are shown in the result. absorption from a larger volume of air is t o be made, 2-Sizing does not increase the tearing resistance t o then bulbs C and D should be larger and bulb A should such a n extent as it does other tests. have a capacity of 40 or 45 cc., b u t the volume of 3-The apparatus is simple and depends upon no bulb B should not be changed. It is applicable t o both light and springs or gauges. heavy papers. 4-The amount of grain in the paper is shown. S-T‘he load is applied with a n unchanging rate of increase. DISADVANTAGES O F TEARING-RESISTANCE T E S T
I-The testing is tedious. 2-There is a n apparent disadvantage due t o t h e sensitiveness of the test in t h a t the individual tests on the same sample vary so greatly t h a t even the average of these tests appears unreliable until i t is observed t h a t the tearing-resistance numbers of different grades of paper show much greater distinction between t h e grades t h a n t h e corresponding Mullen, Ashcroft, or Schopper tests. I n a series of tests on Manilas, the Mullen tests ranged from I O t o 97, while t h e tearingresistance figures ran from 15 t o 450. I n sensitiveness, the tearing-resistance tester resembles the Schopper folding machine. The above method of testing t h e strength of paper is not submitted with t h e idea t h a t i t is t h e final word in paper testing, but only t o awaken interest in_developing more satisfactory methods of specifying paper quality.
B ?SC
PRINTINQ PLANTLABORATORY AND COMPANY SEARS,ROEBUCK CHICAGO, ILLINOIS
ABSORPTION PIPETTES By E. VAN ALSTINE Received July 13, 1918
While using the Parr carbon apparatus for determining both carbonate and total carbon in soils, i t seemed desirable t o have an absorption bulb which would be effective and rapid, and yet which would not contain glass beads or glass rods. I n order t h a t t h e absorption may be complete a n d rapid i t is necessary t h a t t h e gases come in close contact with t h e absorption liquid and if beads or rods are t o be dispensed with the next best means is t o bubble the gas through t h e liquid. The accompanying diagram is of an apparatus designed by t h e writer t o accomplish this. The size here shown is best for absorption of a volume of carbon dioxide up t o I O O cc. from a volume of IOO t o 2 0 0 CC. of air. Bulb A has a n outside diameter of about 2 2 mm. and a capacity of 35 cc.; bulb B, a n outside diameter of about 2 0 mm. a n d a capacity of 2 5 cc Bulbs B and C together should hold as much as the volume of t h e unabsorbed gas, and bulb D.
When gas enters a t a, i t quickly forces t h e liquid from tube b and bulb B through tube G into bulb C. Such gas as still remains t o be forced into t h e pipette must pass through bulb E, the sides of which are being continually wet by t h e liquid dripping slowly through the capillary tube E. It must then bubble through this liquid, which collects in the lower bend of tube G. By t h e time bulb A is about half emptied, all of the gases have been forced out of t h e carbon apparatus and in a few more seconds A will become emptied, about half filling bulb B. While this is taking place t h e gas which filled B is forced through tube b into bulb A, t h u s being kept in motion. When bulb A is emptied t h e largest part of t h e gas has been trapped in bulb C by t h e liquid in bulb B, and when drawn back into t h e Parr apparatus it must bubble through this liquid. It is not necessary t o shake t h e apparatus t o insure rapid action as must be done when bulbs without
