312 



Appendix I. On methods 



tube is put on to the large rubber tube. The operation is that already described 

 except that the tipper tap of the sampling tube, not that of the burette, is that 

 which is rapidly opened and closed. 



The gas is transferred to the Haldane's apparatus for analysis in the following 

 way. A small piece of bent capillary glass tubing is joined by rubber junctions 

 to the sampling tube and the gas burette of the Haldane's apparatus. The dead 

 space is filled with mercury. The lower tap of the sampling tube is connected 

 with a mercury burette such as shown in Fig. 150 ; the dead space here is filled with 

 mercury also. A sample of the gas is then taken over into the gas burette, its place 

 being filled with mercury from the mercury burette. 



FIG. 154. 



To expose the blood in a tonometer at a known temperature. 



This is done in a water bath. According to the circumstances and the scale on 

 which the experiment is being performed, one of two methods may be adopted. 



Method I is a laboratory method which is best adapted for use where power can 

 be obtained and is suitable for the investigation of a number of different samples at 

 a time. The plant which I have is for five tonometers ; these might for instance 

 contain the samples of the same blood exposed to gas containing five different oxygen 

 pressures and thus five points on a dissociation curve might be obtained ; or on the 

 other hand the tonometers may all be filled with different samples of blood and 

 exposed to similar atmospheres as in experiments for the determination of the 

 alkalinity of the various samples of blood. 



The bath consists of a brass cylinder or barrel 44 cm. in height and 16 cm. in 

 diameter. This cylinder is mounted horizontally on bearings from which it can be 

 taken by simply lifting it, it being kept in place by a weak spring. One end of the 

 cylinder screws off, the spindle attached to this and which rests on the bearing is 

 hollow ; through this a thermometer may be inserted. On the spindle at the other 

 end a V-pulley is attached by which the cylindrical bath is geared by a belt to some 



