Abstract
This requires 5 minutes for human blood, unless a little sapanin has been added to the ammonia, in which case 15 seconds may suffice for the laking.
The apparatus for determining carbon dioxid in blood, described in the Proceedings for the meeting April 21, 1915, can be used with equal facility and accuracy for determination of oxygen. 6 c.c. of ammonia made by diluting the concentrated solution with 200 parts of water, are introduced into the apparatus with 5 drops of caprylic alcohol. The apparatus is evacuated and the air extracted from the ammonia by shaking for a few seconds. The extracted air is expelled and the process completed to make certain that none is left.
2 c.c. of blood are then introduced. The blood and ammonia are mixed and allowed to stand until the blood is laked. Then half a c.c. of saturated potassium ferricyanide solution is introduced (the cyanide solution is made air-free by boiling or by shaking in an evacuated flask, and is kept in a burrette under a layer of paraffin oil two or three centimeters thick to exclude air). The apparatus is now evacuated, shaken and the oxygen set free determined exactly as is carbon dioxid. The solubility of oxygen in water is so slight that no correction is made ¢or what remains in solution. The only correction necessary is for the small amount of nitrogen gas which 2 C.C. of blood contain.
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