^'"MaT'iyt'"''}      Apparatus  for  Estimating  Urea.  223 
with  0*15  grms.  of  urea,  the  barometer  being  at  30,  and  the  ther- 
mometer at  6o°F.  the  volume  of  the  nitrogen  disengaged  and  collected 
over  water  was  found  to  be  55  c.c,  a  result  almost  identical  with  that 
obtained  by  Russell  and  West. 
The  apparatus  which  I  have  devised  for  the  estimation  of  the  urea 
is  materially  different  from  that  employed  by  Russell  and  West.  It  is, 
I  think,  more  simple,  more  easily  worked,  and  will  give  results  of  at 
least  equal  accuracy.  It  also  possesses  the  advantage  that  the  mate- 
rials for  its  construction  are  to  be  found  in  every  laboratory.  They 
are  : 
1.  A  glass  measuring  tube  of  about  a  foot  in  length,  drawn  out  at 
the  end,  which  will  be  uppermost  when  the  tube  is  used,  like  a  Mohr's 
burette,  and  subdivided  into  30  parts  of  equal  capacity,  the  aggregate 
volume  of  which  is  55  c.c. 
2.  A  small  wide-mouthed  gas  bottle  of  about  60  c.c.  capacity. 
3.  A  short  test-tube  of  about  to  c.c.  capacity,  and  of  such  height 
that  when  introduced  into  the  gas  bottle  it  will  stand  within  it  in  a 
slightly  inclined  position. 
The  following  are  the  arrangements  for  combining  the  apparatus  and 
working  an  experiment  : 
The  graduated  tube,  held  in  a  clamp  attached  to  a  retort  stand,  is 
depressed  into  a  glass  cylinder,  nearly  filled  with  water,  until  the  zero 
mark,  which  is  near  the  upper  end,  exactly  coincides  with  the  surface 
of  the  water.     15  c.c.  of  the  hypobromite  solution  (100  grms.  of 
NaHO,  250  c.c.  of  water,  25  c.c.  of  bromine)  having  been  poured 
into  the  flask,  the  test-tube  containing  the  urine  is  introduced  by  means 
of  a  forceps,  care  being  taken  that  none  of  its  contents  shall  spill  into 
the  hypobromite.    The  flask  is  now  closed  with  a  very  accurately  fit- 
