3/0  Valuation  of  Crude  Carbolic  Acid.  {^SSt^aE111, 
It  has  been  pointed  out  by  Dr.  E.  R.  Squibb  (Ephemeris,  Vol.  I, 
p.  328)  that  the  solubility  test  of  the  Pharmacopoeia  is  impracti- 
cable, as  it  will  reject  all  samples  not  composed  mainly  of  crystalliz- 
able  phenol,  excluding  cresols  and  xylenols  except  in  small  quanti- 
ties. A  sample  containing  96  per  cent,  of  the  less  soluble  phenols 
never  came  within  16  per  cent,  of  the  requirements.  This  is  applied 
to  the  test  given  in  the  U.S. P.  of  1880,  which  is  practically  the 
same  as  the  present  one.  This  latter  reads  as  follows:  "If  50  vol- 
umes be  thoroughly  agitated  with  950  volumes  of  water,  the  undis- 
solved portion  should  not  exceed  5  volumes,  or  10  per  cent,  by  vol- 
ume of  the  acid."  Dr.  Squibb  proposed  the  following  modification: 
"  Mix  50  volumes  of  the  sample  with  1,000  volumes  of  water  in  a 
vessel  of  2,000  volumes  capacity  and  shake  actively.  Allow  to 
separate,  pour  off  the  upper  milky  fluid,  add  500  volumes  of  water 
to  the  residue  and  again  skake  vigorously  and  set  aside  to  separate. 
Again  pour  off  the  watery  liquid  and  transfer  the  residue  to  a  meas- 
uring cylinder.  The  undissolved  residue  from  crude  carbolic  acid 
No.  1  should  not  be  more  than  5  volumes,  from  No.  2  not  more 
than  18  volumes,  and  from  the  crude  carbolic  acid  of  the  market 
not  more  than  25  volumes." 
H.  W.  Jayne  (Am.  Jour.  Pharm.,  1894,  P-  1 19)  states  that  a  60  per 
cent,  acid  answered  the  requirements  of  the  Pharmacopoeia,  but 
after  distillation,  to  remove  tarry  matter  and  about  1 1  per  cent,  of 
water,  showed  30  per  cent,  insoluble. 
It  is  evident  that  the  solubility  test  is  apt  to  mislead  in  several 
particulars.  Intended  to  exclude  inert  "tar-oils,"  it  excludes  the 
valuable  cresols  as  well.  The  presence  of  a  large  quantity  of  water, 
which  may  reach  20  per  cent,  or  more  without  possible  detection  by 
the  official  tests,  will  correspondingly  increase  the  solubility  of  the 
acid  in  water,  vitiating  the  test  completely. 
A  fractional  distillation  will,  of  course,  give  quite  serviceable 
results  in  approximately  indicating  the  quantities  of  phenol,  cresols, 
xylenols  and  water  present,  and  supersaturation  with  caustic  soda 
solution  and  extraction  with  ether  will  serve  as  a  rough  estimation 
of  bases  and  hydrocarbons.  But  these  methods  are  too  tedious  and 
time-consuming  for  the  use  of  the  pharmacist,  who  is  in  need  of 
methods  requiring  little  time  and  attention. 
Dr.  Charles  Rice,  at  whose  request  the  writer  took  up  this  sub- 
ject, suggested  that  Koppeschaar's  bromine  solution  might  possibly 
