ON  TESTS  FOE  THE  PURITY  OF  GLYCERIN. 
119 
A  portion  of  Nos.  1,  2  and  3  was  incinerated  in  a  platinum 
vessel ;  the  last  two  left  a  scarcely  observable  residue  of  fixed 
substances.  The  fixed  residue  from  No.  1  was  more  apparent, 
larger  in  bulk,  but  small  enough  to  be  of  no  consequence  in  an 
otherwise  unobjectionable  preparation. 
Undiluted  glycerin,  Nos.  1,  2  and  3,  mixed  with  twice  the  bulk 
of  95  per  cent,  alcohol,  yielded  clear  mixtures ;  a  few  drops  of 
sulphate  of  soda  or  gum  water  rendered  them  turbid. 
The  original  samples,  1,  2  and  3,  mixed  with  twice  the  bulk  of 
pure  concentrated  sulphuric  acid,  produced  clear  mixtures  with- 
out change  of  color  ;  a  single  drop  of  simple  syrup  added  to 
them  (glycerin  about  half  a  fluidrachm)  instantly  changed  the 
color  to  brown,  deepening  in  a  minute  to  brown  black,  whereby 
the  liquid  lost  its  transparency.  A  drop  of  gum  water  added  to 
the  mixture  of  sulphuric  acid  and  glycerin,  after  it  had  been 
standing  for  several  minutes,  re-acted  very  slowly ;  but  if  pre- 
viously mixed  with  the  glycerin,  the  addition  of  two  volumes  of 
sulphuric  acid  instantly  caused  a  brown  color,  which  rapidly  deep- 
ened to  a  very  dark  reddish  brown. 
These  experiments  prove  that  minute  quantities  of  inorganic- 
substances,  and  likewise  all  the  organic  compounds  which  are 
likely  to  be  used  to  adulterate  glycerin,  can  be  very  readily  de- 
tected b  v  applying  the  necessary  tests  intelligently,  and  that  they 
will  give  a  correct  estimate  of  its  purity. 
I  have  seen  a  circular  regarding  the  "Vienna  "  glycerin,  which 
stated  that  it  was  equalled  only  by  Price's  glycerin.  Striking- 
out  the  little  word  "  only  "  I  subscribe  to  this  with  this  addition, 
that  Price's  even  far  surpasses  this  new  article,  if  I  can  rely  on 
a  series  of  similar  experiments  made  with  it  some  eight  or  ten 
years  ago ;  and  with  this  farther  addition,  that  Bower's  glycerin 
ranks  with  the  best  in  our  market,  and  that  I  prefer  it  even  to 
Price's,  because,  «as  far  as  I  may  judge  from  my  individual  con- 
ceptions, it  is  almost  absolutely  bland  to  the  taste,  while  Price's 
leaves  a  sense  of  acrimony  in  the  throat. 
I  should  regard  a  glycerin  as  unobjectionable  for  medicinal 
purposes,  if  it  forms  a  colorless  mixture  with  twice  its  volume  of 
strong  alcohol  and  of  sulphuric  acid  ;  and  if,  after  previous  di- 
lution with  distilled  water,  it  yields  no  turbidity,  either  cold  or  on 
