INDUSTRIAL AND ENGINEERING CHEMISTRY
742
centration of certain components must occur at the interface due to adsorption effects. To date no method has been available for the measurement of interfacial tension of solidliquid systems such as we are considering. Accordingly it has not been possible to determine the effect of the individual components upon the interfacial tension values of the system. Subsequent papers from this laboratory will take up the question of the adhesion tension of solutions against solids and will attempt to relate such factors as adsorption, interfacial tension, and adhesion tension. It is conceded that the adhesion tension data presented herein are not to be taken as representing definite and characteristic values for systems of solid and pure liquid, but that they do in fact furnish data representing the energy changes which occur when the solid and liquid phases in question come in contact. They are believed to give values representing the degree of wetting in each case. Flooding Agents In practice certain solutes have been added to water for the purpose of increasing the effectiveness of the drive of
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Vol. 20, No. 7
oil from the sand. Solutes such as sodium carbonate, known as "flooding agents," have been used. Thus far no data are available in the literature relative to the adhesion tension of aqueous solutions with a solid. It is to be expected that the addition of certain solutes would alter the adhesion tension of water. If this is true, the displacing tendencies of different aqueous solutions for a given oil from silica should be quite different. It is believed that an application of the adhesionrtension method to the study of the behavior of aqueous solutions should throw light on the functions of flooding agents. For example, it may be possible to determine whether the more active flooding agents actually do react chemically with the sand, as has been contended by Nutting* and others. Acknowledgment
The authors wish to acknowledge their indebtedness to E. H. Leslie, of the Department ?f Chemical Engineering, for his assistance in procuring samples of crude oils for this investigation. /
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A Micro Saybolt-Type Viscosimeter' Stuart M. Rogers and Linden R. Adkins VACUUM OIL COMPANY, ROCHESTER, N. Y.
PPARATUS for determining the viscosity of small samples of lubricating oil has usually been of glass. Capillary tubes, of which the Ostwald is perhaps the best known, are used for determining absolute viscosities. For comparisons with the results by standard types of metal viscosimeters a glass pipet has been in common use. A very efficient and accurate one of this type was described by Doctor Ferris at the Detroit meeting of AMERICAN CHEMICALSOCIETY. Such apparatus has the usual disadvantages of glassware for routine testing of being fragile, hard to clean, and not easily duplicated. A metal viscosimeter has been designed which has all the ruggedness and adaptability of the Saybolt Universal, can be made to fit into any usual form of hot or cold bath, and takes as little as 8.5 ml. of sample. Its essential outside dimensions are those of the Saybolt tube, and the dimensions of the barrel are nearly proportional to the Saybolt, being 6.7 cm. high and 1.43 em. in diameter. The outlet tube comes within the tolerances of the Saybolt Universal. When the sample available is of at least 12 ml., manipulation is according to usual practice (A. S. T. M. D88-26) except that a 10-ml. graduated cylinder is used to replace the usual 60-ml. flask and 7 ml. are run out. If there be just sufficient sample to fill the barrel, a cover may be plabed on the top of the whole apparatus and the viscosity taken after standing for a half hour or so for the sample to come to temperature. To obtain the ratio of Saybolt Universal to one of these new viscosimeters, the viscosities of a number of oil samples having a fairly wide range were determined in both instruments. From 100 to 2500 seconds Saybolt Universal this ratio varied from 4.8 to 5.1, average 4.96. The determinations were made at 77' F. (25' C.) to eliminate the cooling error. Other comparisons of a number of samples a t 104' F. (40'
A
1 Presented before the Division of Petroleum Chemistry at the 75th Meeting of the American Chemical Society, St. Louis, Mo., April 16 to 19, 1928.
C.) gave the same ratio, indicating that the cooling error a t this temperature is less than errors of manipulation. At 210" F. (98.9" C.) over a range from 100 to 214 seconds Saybolt Universal, the ratio varies from 5 to 5 . 1 , a v e r a g e 5.05. This higher r a t i o i s probably due to the cooling error. As it seems to be reasonably constant, however, a closer approximation to S a y b o l t viscosities at 210' F. (98.9' C.) is possible with this instrument t h a n with one in which the sample is kept a t a c o n s t a n t temperature throughout. C h e c k t e s t i n g is well within the tolerance of the Saybolt Universal. It is, of course, subject to the c o m m o n manipulat i o n e r r o r s of that instrument-fibers across the outlet tube, neglect to pipet out the overflow chamber, a gradual accumulation of resinous material in the outlet tube, Micro Saybolt-Type Viscosimeter and so on. Capacity, 8.4 ml.; including overflow 12.0 ml. ~~
