Jan., 1919
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Manilas t h a n krafts. The old “point per pound” should hold somewhat more than this volume so t h a t standard is a fairly reliable one in the 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 outthan the Mullen test would indicate. ‘side diameter of the 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., but the volume of bulb B should not be changed. 3-The apparatus is simple and depends upon no 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 the 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 the grades than the 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 the 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 the strength of paper is not submitted with the idea t h a t i t is the final word in paper testing, but only t o awaken interest in_developing more satisfactory methods of specifying paper quality.
B ?SC
PRINTINQPLANTLABORATORY 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 the absorption may be complete and rapid i t is necessary t h a t the gases come in close contact with the absorption liquid and if beads or rods are t o be dispensed with the next best means is t o bubble the gas through the liquid. The accompanying diagram is of an apparatus designed by the 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. and a capacity of 2 5 cc Bulbs B and C together should hold as much as the volume of the unabsorbed gas, and bulb D.
When gas enters a t a, i t quickly forces the liquid from tube b and bulb B through tube G into bulb C. Such gas as still remains t o be forced into the pipette must pass through bulb E, the sides of which are being continually wet by the 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 the time bulb A is about half emptied, all of the gases have been forced out of the carbon apparatus and in a few more seconds A will become emptied, about half filling bulb B. While this is taking place the gas which filled B is forced through tube b into bulb A, thus being kept in motion. When bulb A is emptied the largest part of the gas has been trapped in bulb C by the liquid in bulb B, and when drawn back into the Parr apparatus it must bubble through this liquid. It is not necessary t o shake the apparatus t o insure rapid action as must be done when bulbs without
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beads or rods are used, yet absorption is as rapid as with either. These pipettes may be made by any good glass blower, or they may be obtained for about $ j . o o each from Mr. Paul Anders, Urbana, Illinois. COLLEGE O F AGRICULTURE os ILLINOIS UNIVERSITY URBANA,ILLINOIS
NEW REFLUX CONDENSER By JAMESJ. BAJDA Received July 10, 1918
Vol.
11,
No.
I
MELTING POINT OF ROSIN BY T. LINSEY CROSSLEY Received August 2, 1918
Certain large buyers of rosin have recently specified a melting point limit for this material. Samples have been submitted for this test, but without specifying how the test was to be carried out. Properly speaking, rosin, like asphalt, has no definite melting point, therefore, any specification aiming t o grade it by reference t o its behavior on heating should state the method for obtaining results. Schwalbe and Kuderlingl not only state melting points but record results to fractions of one degree and claim t o differentiate between certain rosins by their melting points. Several methods have been used t o determine t h e quality of rosin as indicated by its action on heating. The closed capillary tube, of such general application, is used largely but, unless conditions of heating and observation are closely controlled, results are not uniform with different operators. The following results were obtained on t h e same four samples b y methods indicated:
A modified type of reflux condenser, applicable t o most kinds of laboratory work, has been found very satisfactory, especially in those cases in which t h e refluxing liquid has a comparatively high boiling point. In the usual type of reflux condenser, hot vapors enter the relatively cold por1/4 in. l/s in. tion of the cooling chamber Column Column Film Capillary Rosin F. F. F. F. and allow the condensed 169-172 150 146 1 . . .......... 174-184 liquid t o collect in the inner 172-183 169-172 146 145 ... 165-173 ... 154(a) tube, until overbalancing 2 ............ 176-187 174-182 147 154 174-185 167-176 155 147 pressures therein cause the ... 156 153 liquid t o spurt back into 3 ............ 161-167 149-15 1 120(b) 128 161-157 145-146 134 130 the receiver. This spurting ... ... 126 ... back is often not very 4 . . . . . . ...... 153-155 145-147 135 138 147-155 144-145 133 136 desirable, especially as the 149- 153 ... ... ... ( a Heated until clear. receivers are usually made ( b ] Probably mechanical weakness of film. of glass. The first three methods were carried out as follows: The improvement here is obvious from the ac- Glass tubes of about S/le in. inside diameter and 2 in. companying drawing and long were prepared. These were dipped in melted consists of a vapor conduit, rosin so that on cooling there was left inside the tube a column of rosin of the required depth. I n the case 2 , forming a part of the adapter of the condenser I , of the method marked “Film” the foot of the glass through which the vapors tube was heated slightly and applied carefully t o t h e pass and are led therefrom surface of the molten rosin so that upon cooling a into the upper part of thin film only of t h e rosin was formed. The tubes the condensing coil 3. The were attached to the thermometer in such a way that condensate flows into the the bottom of the tube with t h e rosin was located trap 4, by means of which about the center of the mercury bulb. The theris provided regular and mometer with tube attached was immersed in cold undisturbed flow into the water in a 400 cc. beaker with the bottom of the rosin receiver. Any tendency t o column I in. below the surface. The temperature disturb the balanced rela- was raised about 3’ per minute. I n the cases of 1/4 in. and in. columns, it will be tion of the condensed liquid in the trap will find outlet noted that two temperatures are given. The lower through one arm of the temperature indicates the point a t which the rosin Y-tube which leads up- is soft enough for the water t o enter t h e tube, the wardly and axially, 5, other being the point a t which the water breaks through. The result is of course merely the point a t which t h e through the cooling coil 6. The flow of c o o h g water viscosity is so reduced that it is overcome by the in a direction opposite t o pressure of I in. of water. It is necessary t h a t t h e t h a t of the condensates diminishes the strain on the heating should be well regulated. If heat is applied too rapidly it will naturally result in a higher final glass. temperature and a wider spread between t h e two points. FLUSHING, I,. I. .
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N E W YORK
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“Rosin Studies,” J. SOC.Chem. Ind., SO, 1397.
