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New techniques for calibrating the Lloyd—Haldane apparatus
Author(s) -
Cormack R. S.,
Heath J. R.
Publication year - 1974
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1974.sp010547
Subject(s) - mathematics , decimal , value (mathematics) , graduation (instrument) , statistics , arithmetic , geometry
1. A new way of measuring the graduation error in the stem of the Lloyd—Haldane burette is described, in which a fixed mass of water is made to occupy different parts of the stem. This gave the same answer as the gravimetric method, but was much easier. 2. Two independent methods of measuring the ‘meniscus error’ gave values of 0·006 and 0·008 ml. respectively. It is concluded that the bulb volume can be measured gravimetrically with the burette inverted, provided that the value so obtained is corrected by adding about 0·007 ml. 3. Alternatively, this estimation can be made with the burette the right way up, no correction then being needed. To do this the lower end of the burette must be blocked and a method of doing this without the need to fuse on a glass tap is described. 4. After calibration by the above methods analyses on fresh air for CO 2 + O 2 gave a mean value of 20·98%, which, in the authors’ view, is the correct value. 5. The observer error was measured and from this the theoretical maximum accuracy of gas analysis by Haldane's method was calculated. It is concluded that the calculated% should be correct to the second decimal place in about half the analyses, the rest having an error of ± 0·01%. Results approaching this were obtained.