A handy method of determining the amount of carbonic acid in air / by William Mackie.

  • Mackie, William.
Date:
1905
Catalogue details

Licence: In copyright

Credit: A handy method of determining the amount of carbonic acid in air / by William Mackie. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    possible sometimes to come closer, but for most part within half a minute is probably the nearest approximation that could be made by the most careful observer—the time, from the conditions of experiment, really not being capable of more exact determination. But even when the nearest full number of minutes is noted, provided that the number does not fall too low, say below 10, the results will be found sufficiently accurate for most purposes. Quantity of solution in a 'drop’ or ‘spot,’ and variations in the diameter of the ‘ spots. ’ As regards the size of the drops it may be stated that the two 50 c.c. stoppered burettes with which the determinations were made both gave us nearly as possible 22 drops per c.c. (one drop = '045 c.c.) when discharging at the ordinary rate at which the spots are made. This is therefore considered the standard drop. There is no doubt considerable variation in burettes in this respect, but from an investiga- tion which has been made on my behalf in regard to this point it would appear that there is likely to be no difficulty in procuring burettes of similar calibre to those which I used. It may be remarked that small deviations from the quantity indicated may be safely discounted, as drops of larger size on falling the same distance as smaller drops spread out to spots of larger diameter than the smaller, thus tending towards com- pensatory adjustment as regards their depth. As will be readily under- stood it is really the depth of the spot which is the important dimension from our present point of view. A drop of the standai’d size if it falls about I inch gives a spot about 9 mm. in diameter. The tabulated results which accompany this paper, unless where otherwise stated, were made from the observation of spots of that diameter. Where the spots vary in diameter their times of discharge as before indicated are inversely as the square of their diameters, so that it is comparatively easy to reduce the time results obtained from the observation of spots of abnormal size to the time results of normal-sized spots. If we have spots say of 8, 9, and 10 mm. diameter respectively, but containing the same quantity of liquid, their times of discharge for the same atmosphere will be as the reciprocals of the squares of these numbers, or as TCT- The following rule may be given for the reduction of the time of spots of abnormal diameter to the time of spots of normal diameter. If the spot is 8 mm. in diameter multiply the time by if 10 mm.