[VIL


{h.)  Prick  the  finger  as  in  7  with  the  instrument  supplied  for  the  purpose.
Fill  the  short  automatic  capillary  japette  tube  with  blood.  Its  capacity  ia
6.5  c.mm.  In  filling  the  tube,  hold  it  horizontally.  See  that  no  blood
adheres  to  the  surface  of  the  tube.  This  can  be  done  by  having  the  pipette
slightly  greasy  on  the  outer  surface.
(c.)  Dissolve  the  blood  obtained  in  {b.)  in  the  water  of  the  blood-compart-
ment {(i),  washing  out  every  trace  of  blood  from  the  pipette.  Mix  the  blood
and  water  thoroughly.  Clean  the  pipette.  Then  fill  the  blood  compartment
exactly  to  the  surface  with  distilled  water,  seeing  that  its  surface  also  is  per-
fectly level.
{(l.)  Arrange  a  candle  in  front  of  the  reflector  (S) — which  is  white,  and  with
a  smooth  matt  surface  made  of  plaster-of-Paris— so  as  to  throw  a  beam  of  light
vertically  through  both  compartments.  Look  down  vertically  upon  both
compartments,  and  move  the  wedge  of  glass  by  the  milled  head  (T)  until  the
colour  in  the  two  compartments  is  identical.  Read  ofiF  the  scale,  which  is  so
constructed  as  to  give  the  percentage  of  hemoglobin.
