300 



Appendix I. On methods 



The apparatus consists of a manometer of 0'5 mm. bore glass tubing. At the top 

 of each limb of the manometer is a three-way tap with 

 a T boring. Of the three ways of each tap one opens to 

 the open air, the other goes to the blood gas bottle. The 

 blood gas bottles are of the shape indicated in the figure ; 

 they are each about 3 c.c. in capacity up to the top, and 

 should of course be identical in size. The apparatus is 

 fixed to a wooden stand, fitted to a clip by which it hangs 

 on the edge of the water bath. 



There are certain practical details about which the buyer 

 of one of these pieces of apparatus should satisfy himself : 



(1) That the tubing of the manometer is not more 

 than O'o c.c. bore. 



(2) That the point at which the fine tubing of the 

 manometer joins the coarser tubing of the tap should be 

 above, not below the bend of the tubing. 



(3) That when the manometer hangs in the water bath 



with the tubing vertical the bottles should be completely submerged in the water. 



(4) That the clip be hung in such a position that the apparatus can stand in 

 the bath with the bottles vertical or nearly so. 



FIG. 138. 



FIG. 139. Correct position of junction 

 between fine and coarse tubing. 



FIG. 140. Incorrect do. 



FIG. 141. 



FIG. 142. 



