^"'jan"''iSlf' "  ■  1"  '       ^^^^      Scdicln,  23 
Finally,  four  experiments  were  very  carefully  instituted^  using  ana- 
lytical weights  and  bulb  and  scale  pipettes,  the  correct  relation  of 
which  to  the  weight  used  had  been  demonstrated.  The  following 
solutions  were  made: 
1  gram  of  salicin  in  2S  cc.  of  distilled  wa^er. 
1  gram  of  salicin  in  25  cc.  of  distilled  water. 
1  gram  of  salicin  in  28  cc.  10  per  cent,  solution  of  glycerin. 
1  gram  of  salicin  in  25  cc.  10  per  cent,  solution  of  glycerin. 
All  were  dissolved  by  heat  at  the  same  temperature,  each  filtered 
until  perfectly  free  from  floating  particles,  and  set  aside.  After  twenty- 
four  hours,  although  the  temperature  had  fallen  to  about  53° F.,  all 
were  j)erfeGtly  bright.  But  on  dropping  a  minute  crystal  of  salicin 
into  eich  bottle,  both  the  aqueous  and  glycerin  solutions  I  in  23 
became  cloudy  in  half  an  liour,  from  the  appearance  of  crystals ;  that 
containing  glycerin  more  so,  giving  a  very  abundant  crop  in  another 
twenty-four  hours;  the  crystals  in  the  a(|ueous  solution  did  not  increase 
much  in  that  time.  Both  the  1  in  25  solutions  remained  bright  after 
the  second  twenty-four  hours. 
The  solubility  of  salicin  in  water  at  ordinary  temperatures  may 
therefore  be  taken  as  1  in  28  for  cold  solution,  1  in  24  if  previously 
dissolved  by  heat.  For  dispensing  purposes,  of  course  the  lower  solu- 
bility, 1  in  28,  must  be  taken  as  the  standard. 
The  Decomposition  of  Sallcdii  on  Heating  with  Glyoerin, — 1  drachm 
of  salicin,  tinely  powdered  and  triturated  with  drachm  of  glycerin, 
transferred  to  a  test-tube  containing  a  thermometer  and  gradually 
lieated,  dissolves  without  apparent  decomposition  at  about  300°F. ;  if 
diluted  to  2  ounces  with  water,  a  colorless  solution  is  obtained,  crys- 
tallizing abundantly  on  cooling. 
Heated  beyond  300°F.,  the  mixture  of  salicin  and  glycerin  boils, 
rapidly  acquires  a  brown  color  and  an  odor  of  caramel ;  if  now  diluted 
a  brown  solution  with  burnt  odor  is  obtained,  which  also  crystallizes 
abuiuhuitly  on  cooling. 
The  same  proportion  of  salicin  and  glycerin,  heated  for  half  an 
hour  to  500°F.,  continues  to  boil,  gives  off  water  and  sutlbcating 
vapors  (partly  due  to  acrolein)  and  the  vapor  of  salicylol,  the  licpiid 
becomes  deep  red-brown  but  remains  transparent  at  5()0°F. ;  it  l)ecomes 
opa(iue  at  460°F.,  and  solidifies  on  cooling.  Warmed  with  water  to 
two  ouncefe,  it  became  milky  and  a  large  amount  of  brown  matter 
