PURITY  OF  YELLOW  BEESWAX. 
537 
suits,  and  conclude  with  a  few  remarks.  The  melting-point  pre- 
sents a  little  difficulty,  and,  after  trying  various  methods,  it  was 
found  better  to  take  the  solidifying-point.  A  test  tube  contain- 
ing about  100  grains  of  wax  was  immersed  in  hot  water  in  a 
beaker  until  perfectly  melted.  A  thermometer  was  inserted  in 
the  tube  and  the  water  allowed  to  cool  gradually,  the  wax  being 
constantly  stirred  until  the  bulb  of  the  thermometer  could  not 
be  seen  when  in  the  middle  of  the  wax.  The  temperature  then 
remains  steady  during  the  solidification  for  about  two  minutes, 
and  there  is  no  difficulty  in  getting  the  same  result  any  number 
of  times  within  half  a  degree. 
The  presence  of  paraffin  is  shown  by  the  low  melting-point, 
but  nJ idea  of  its  amount  can  be  obtained  from  the  degree  shown, 
owing  to  the  varying  melting-points  of  different  samples  of 
pstraffin.  The  only  method  of  determining  the  amount  of 
paraffin  found  at  all  practical,  consists  in  destroying  the  wax 
with  fuming  sulphuric  acid.  50  grains  of  the  wax  with  IJ  oz. 
by  measure  of  fuming  sulphuric  acid,  are  put  into  a  small  beaker 
holding  about  5  oz.,  and  gradually  heated  in  a  water-bath.  Great 
care  must  be  taken  to  stir  it  very  slightly  at  first,  especially  if 
only  a  small  quantity  of  paraffin  is  present,  as  the  action  is  apt 
to  become  unmanageable.  When  the  violence  of  the  action  is 
over,  the  heat  is  raised  to  100°  C.  for  about  an  hour  and  a  half 
and  the  mixture  occasionally  stirred.  It  is  then  left  to  cool 
very  slowly  in  the  water-bath,  and,  when  quite  cold,  the  paraffin 
will  be  found  forming  a  layer  on  the  black  semi-liquid  mass.  It 
is  carefully  removed,  washed  with  water  to  remove  as  much  of 
the  adhering  acid  as  possible,  dried,  and  again  heated  for  an 
hour  in  a  smaller  beaker  with  J  oz.  of  the  acid.  This  gives  the 
paraffin  perfectly  white,  and  it  is  then  washed,  dried  and  weighed. 
There  can  be  no  doubt  that  there  is  some  loss,  as  the  common 
paraffin  employed  contains  coloring  matters  destroyed  by  the 
acid  ;  but  I  know  of  no  other  method  at  all  useful,  though  I  have 
carefully  tried  some  which  have  been  proposed. 
For  the  estimation  of  rosin,  the  action  of  cold  alcohol  seems 
sufficient.  To  90  grains  of  pure  wax,  10  grains  of  rosin  were 
added,  by  melting  them  together  and  thoroughly  incorporating. 
On  exhausting  with  cold  alcohol,  by  rubbing  the  wax  in  a  mortar 
