274  Glycerin  as  it  Exists  in  Commerce.  {AjUn°ei;Sra^ 
QUALITY  OF  GLYCERIN  AS  IT  EXISTS  IN  COMMERCE. 
By  Alfked  Henry  Mason,  F.  C.  S. 
From  a  more  extensive  paper,  treating  of  the  chemical  history,  its 
various  applications,  &c,  we  extract  the  part  relating  to  the  quality 
of  the  commercial  article. 
Many  impurities  are  necessarily  found  in  crude  glycerin  according 
to  the  process  of  manufacture,  or  the  quality  of  water  used  in  manu- 
facturing ;  for  industrial  purposes  these  impurities  are  not  objection- 
able or  disadvantageous,  if  only  present  in  moderate  proportions.. 
For  medicinal  use,  of  course,  it  is  absolutely  necessary  that  pure  gly- 
cerin should  be  used,  and  the  glycerin  purified  by  Wilson's  process, 
manufactured  by  Price's  Patent  Candle  Co.,  is  undoubtedly  superior 
to  any  other  I  have  examined.  The  fact  that  Continental  manufac- 
turers now  offer  medicinal  glycerin,  a  la  Price,  inodorous,  etc.,  would 
tend  to  substantiate  this  statement,  and  it  occurred  to  me  that  it 
might  be  interesting  to  know  how  these  various  manufactures  com- 
pare with  Price's  ;  hence  the  ultimate  object  of  this  paper. 
I  have  selected  nine  samples  to  report  upon,  and  these  represent 
English  and  Continental  manufactures. 
The  various  chemical  re-agents,  shown  with  the  results  in  the  tabu- 
lar form  below,  have  been  applied  in  the  usual  way,  standard  solutions 
being  added  to  the  specimen  of  glycerin  (the  glycerin  previously  di- 
luted with  an  equal  bulk  of  water),  excepting  the  argentic  nitrate — - 
one  part  of  solution  was  added  to  four  parts  of  undiluted  glycerin, 
and  the  mixture  allowed  to  stand  24  hours.  The  specific  gravity  was 
taken  at  60°  Fahrenheit,  withBeaume's  hydrometer,  and  several  were- 
taken  by  weight  and  found  to  correspond.  The  odor  is  easily  ascer- 
tained by  rubbing  a  little  glycerin  on  the  back  of  the  hand ;  the  pe- 
culiar mousey  smell  with  some  samples  is  easily  detected,  and  this 
becomes  more  intense  by  heating  a  little  of  the  glycerin  in  a  test 
tube.  Glycerin  mixed  with  an  equal  volume  of  rectified  sulphuric 
acid  should  not  produce  effervescence,  or  coloration,  if  sufficiently 
pure  for  medicinal  use. 
By  adding  absolute  alcohol  and  concentrated  sulphuric  acid  to 
glycerin  on  heating,  a  fruity  smell  is  set  free,  more  or  less  intense, 
owing  to  the  presence  of  butyric  acid  and  (or)  formic  acid ;  the  pe- 
culiar pine- apple  odor  is  very  strong  in  some  samples,  showing  the 
formation  of  butyric  ether. 
