AmNov.?Sarm'}      Commercial  Carbolic  Compounds.  583 
(3)  In  the  presence  of  a  sufficient  excess  of  alkali,  even  a  largely 
diluted  solution  may  be  boiled  down  without  the  slightest  appreciable 
loss  of  phenol  or  cresol. 
(4)  Tar  oils  and  naphthalin  are  only  very  slightly  dissolved  by  the 
alkali,  and  may  be  perfectly  removed  from  the  solution  by  agitating  it 
with  benzol. 
Taking  these  ascertained  facts,  we  apply  them  in  the  following  man- 
ner, taking  each  case  in  turn  : — 
(1)  PROCESS  FOE   THE    VALUATION    OF    A    CARBOLIC    POWDER  IN 
WHICH  THE  BASE  IS  NOT  LIME,  AND  THE  PHENOLS 
ARE  CONSEQUENTLY  NOT  IN  COMBINATION. 
Weigh  out  100  grammes  of  the  powder,  and  transfer  the  same  to  a 
flask,  and  add  400  cc.  of  methylated  spirit ;  then,  having  introduced 
a  well-fitting  cork,  agitate  for  a  minute  or  two  at  intervals  during  an 
hour,  and  finally  set  the  whole  aside  to  settle.  When  subsidence  is 
complete,  pour  or  filter  off  300  cc.  of  the  supernatant  liquid,  which 
thus  represents  75  grammes  of  the  original  powder  actually  taken  for 
analysis.  Here  it  may  be  noted  that  in  laboratories  fitted  with  the 
specially  large  "  Soxhlet"  apparatus  required,  a  more  rapid  and 
economical  method  is  to  mix  the  original  powder  with  bran,  and  to 
extract  it  in  such  an  apparatus,  with  just  sufficient  spirit  to  do  the 
necessary  work. 
To  the  spirituous  extract  of  the  powder,  obtained  as  above  described, 
200  cc.  of  5  per  cent,  solution  of  sodium  hydrate  are  now  added, 
and  the  mixed  liquids  are  evaporated  to  about  half  their  bulk.  At 
this  point  any  tar-oils  or  naphthalin  present  will  separate  out,  and  are 
to  be  removed  by  filtration.  The  filtrate,  freed  from  these  impurities, 
is  now  evaporated  down  to  a  bulk  not  exceeding  50  cc,  and  transferred 
to  a  specially  constructed  measuring  tube  surrounded  by  cold  water, 
the  basin  being  rinsed  out  with  water,  so  that  the  entire  amount  of 
fluid  in  the  tube  shall  be  exactly  65  cc.  The  tube  employed  is  of 
peculiar  form,  capable  of  holding  over  110  cc.  and  is  specially  gradu- 
ated and  stoppered.  It  is  wide  at  the  base,  and  is  narrowed  at  65  cc. 
from  the  bottom  to  such  a  diameter  as  to  show,  when  graduated,  *25 
of  a  cc.  The  first  graduation  is  at  20  cc.  from  the  bottom,  the  second 
at  65  cc,  and  then  the  delicate  graduations  (in  *25  of  a  cc.)  commence 
and  continue  for  45  cc.  more  up  to  110  cc  The  tube  is  furnished 
with  a  long  stirring  rod  made  as  thin  as  possible,  and  projecting  above 
