Since it is practicable to have a net mang of as mu.& as 8 cm. even for a liquid of ension such as alcohol, the overall error in .25 per cent even in student
On the whole, there is no reason why even a routine student setup should not give values accurate to better than one per cent. Once the apparatus has been set up, a whole series 6f measurements can be made in a very short time, since the manometer readings required can be made in less than five minutes and the process of cleaning the tubes after a run and introducing a new sample will take only about another five minutes. The same pair of capillaries can be used indefinitely in the absence of bresksge unless the liner one becomes clogged by dust. This may be avoided by iiltering be kept to less than 0.1 mm. and so the incoming air through a bit of cotton, and in any of magnitude as the error in P. event a new line capillary can be readily standardized by a single run with benzene. The construction and use of the equipment is well tube dips more deeply than the other. In that within the powers of high-school students. The cost s, the difference in depth a t is extremely low as compared to that of thearingor drop weight methods. In conclusion, it is urged that there be more widespread use of this simple, convertient, and A = d sin o rapid technic of surfacetension measurement. d is the distance between the axes of the two and a is the angular departure from the d c a l o rotation about a horizontal axis perpendicular LITERATURE CITED 5", A = 0.9 mm. If the tilt in this direction dow lo,A = 0.17 mm. or less. This error is reduced if the tubes, regardless of a slight ,are adjusted to dip to the same depth.
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(1) ADAM, "The physics and chemistry of surfaces," The &endon Press, Oxford, England, 1930,332 pp. (2) BA-RD AD-, "Capillary action," Cambridge University Press,Cambridge, England, 1883. (3) SWGDEN. J. C h m . Soc., 121, 858 (1822). (4) SUGDEN, i ~ . ,125,27 (1924). (5) ADAM, op. cit., p. 12 ff.
MURAL IN SCIENCE LIBRARY, BRYN MAWR COLLEGE (Frontispiece) ed Burrage ry" in the -
of Albertus Magnus, Roger Bacon, and early alchemists. In the third panel the saolls c o n t i n f @ 0 n ~ & . ~ m r n a t e Iatxo-chemistry and the Phlogiston Th-? whi~h
life. Both m mixture used
