. Public health laboratory work, including methods employed in bacteriological research, with special reference to the examination of air, water and food contributed . tied ; and the finger is thenpricked so that a drop of blood may be made to fall alsointo the jar. The whole is then vigorously shaken up CARBONIC OXIDE. 215 and allowed to stand for a short while, when a little ofthe reddish liquid is removed and examined by thespectroscope, and the appearance on the scale is care-fully noted. The spectral appearance will be that ofoxy-haemoglobin. Oxidised haemoglobin shows two well marked ban
. Public health laboratory work, including methods employed in bacteriological research, with special reference to the examination of air, water and food contributed . tied ; and the finger is thenpricked so that a drop of blood may be made to fall alsointo the jar. The whole is then vigorously shaken up CARBONIC OXIDE. 215 and allowed to stand for a short while, when a little ofthe reddish liquid is removed and examined by thespectroscope, and the appearance on the scale is care-fully noted. The spectral appearance will be that ofoxy-haemoglobin. Oxidised haemoglobin shows two well marked bandsin the yellow and in the green parts of the solar spec-trum, both lying between Fraunhofers lines D and spectral appearance of haemoglobin in the presenceof carbonic oxide is almost identical. A few drops of a solution of ammonium sulphide arenext added, the bottle is well shaken, and the liquid isre-examined. If no change whatever in the spectro-scopic appearance of the fluid has ensued, carbonicoxide is present; otherwise the ammonium sulphide hav-ing de-oxidised or reduced the haemoglobin, the twobands will be represented by a single band, shaded off. Fig. 35.—Showing the characteristic disposition of the absorptionbands, in the spectroscopic picture of oxy- and reduced upper scale representing oxyhaemoglobin and the lower reducedhaemoglobin. at the borders, and occupying a position intermediatewith regard to the original two bands. 2l6 LABORATORY WORK. A Quantitative Test. The subchloride of copper has the peculiar propertyof absorbing this gas ; and advantage is taken of thefact to estimate the quantity present by the method ofeudiometry. It will be unnecessary to repeat here what has alreadybeen described in connection with oxygen and nitrogen;it will suffice to state that a volume of air is measuredin the Hempels burette (at the current temperature andpressure), and then passed over, slowly and repeatedly,into the absorption pipette charged with
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