An’ EASY METHOD FOR DETERMINING VAPORDENSITIES BY PHILIP BLACKMAN
PART IV’
The apparatus here described is an improvement upon that detailed in Part 11. There is no tap, but instead each end of the capillarytube is furnished with a metal rim with screw-thread on the outside on to which fits a solid metal cap. The bore of the capillary-tube must be of medium diameter (not too wide, nor too narrow). ,4 “refill” of the following description will be required. ,4 piece of glass tube has one end softened in the blowpipe flame and drawn off to a long, thin, capillary-end. Mercury, or the liquid to be experimented on, can be sucked up into it, and kept there by simply placing the finger over the wide end. Its capillary-end can then be inserted into the bore of the apparatus and by gently loosening the hold over the wide end a thread of mercury, or of the required substance, of any desired length may be injected. One cap is screwed on to one end of the apparatus. By means of the refill a thread of mercury is inserted in the other end, then a thread of the substance to be experimented on, and finally a second thread of mercury, after which this end is also closed with the screw-cap. The first cap is now screwed off and the required measurements and heating are carried out as already explained. It is possible (and there is not the slightest need t o avoid it) that between the screw-cap and the adjacent mercurythread may be left a short space of the bore not filled with mercury, but containing air. ,4 little consideration will show that this cannot in any way whatever introduce any error, because the value of L is independent of any changes in this Continued from the Journal of Physical Chemistry, 13, 537 (1909).
Easy ;Method
joy
Determining Vapor-densities
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air-space seeing that the other end of the apparatus is open to the atmospheric pressure. Care will have to be taken not to break off the refill within the bore of the apparatus, as it may be found rather difficult to remove the broken glass.
Note t o Parts I-1V The author now sees quite plainly that the two mercurythreads need not necessarily be perfectly contiguous to the thread of substance between them. This being the case the introduction of the respective threads will be rendered much easier. Corrigenda I n the Journal of Physical Chemistry, 13 (1909’): Page 426, in the second foot-note, instead of 5 j o ” read ‘< 715. ” Page 428, line 5, instead of “ 8 7 ” read “ 8 7 , 13;5.” Page 430, line 25, instead of H, 7.2,” read H, h,” in the footnote after “ (1908)” add “ o r Journal of Physical Chemistry, 12, 663 (1908).” Page 431, line 2 1 , after (1908)” add “ o r better, because fuller, Journal of Physical Chemistry, 12, 668 (1908).” Page 433, in the footnote, instead of (‘441 ” read “4141.” Page 434, line 3, instead of “determined” read “are determined.” Line 4, instead of “effected” read ‘‘ is effected.’’ Line 13, instead of “679, 688” read “679-688.” Page 437, line 15, instead of “ t h e quantity” read “ t h e positive quantity. ” Addenda I‘
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The special apparatus briefly described in the (Journal of Physical Chemistry, 12, 677-678 (1908), 13, 4 2 7 (1909) and Zeitschrijt fur physikalische Chemie, 6 3 , 639 (1908)~ 65, 551 (1909), and very fully detailed in the Chemical News, 100, 13 (1909)~is supplied by Messrs. F. E. Becker & Co., Ltd., 17-27 Hatton Wall, London, E. C. (England). The same makers supply the apparatus described in the
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Ph il ip Bla ck ni u 11
Journal of Physical Chew1 istry, I 2 , 684-686, 690-692 ( I 908) or Berichte dev deutsclzen chemischen Gesellschajt, 41, 8 8 1-883, 4111-4144 ( 1 9 0 8 ) ) . The author would be obliged if all those, who feel interested enough t o make inquiries concernin9 the methods and apparatus, would kindly address their communications t o ' + Osborne House, I , Osborne Str., London, E. England) " in order to avoid undue delaJ- in t h e despatch of replies. Huciziii?) Technic Imiztiift Lolldoil, 4 E 'E:7l~lulrci~
