120 
Why  do  Syrups  Spoil? 
.4m.  Jour.  Pharnv 
March,  1901. 
(5)  The  presence  of  substances  which  are  naturally  inclined  to  be 
unstable,  such  as  hydriodic  acid,  hypophosphites,  etc. 
(6)  Fermentation  due  to  the  action  of  yeast  or  other  microbic 
agents. 
(7)  Impurities  in  the  sugar  used  in  making  the  syrup,  e.  g.,  ultra- 
marine, etc. 
On  carefully  examining  these  causes  we  find  that,  with  the  excep- 
tion of  one  or  two,  perhaps,  they  are  all  practically  under  the  con- 
trol of  the  pharmacist,  as  we  shall  see. 
It  is  a  well-known  fact  that  a  syrup  of  proper  density  is  far  less 
prone  to  spoil,  provided,  of  course,  it  be  made  from  proper  ma- 
terials, than  is  a  syrup  made  with  insufficient  sugar.  On  the  other 
hand,  a  too  concentrated  syrup  is  just  as  likely  to  spoil  as  a  weak 
syrup,  because  it  is  equally  well  known  that  a  very  concentrated 
syrup  will  deposit  crystals  of  sugar,  and,  in  so  doing,  will  become 
weaker  in  sugar  than  if  made  with  just  sufficient  sugar.  In  other 
words,  the  latter,  in  crystallizing  out,  leaves  the  syrup  deficient  in 
sugar.  Hence  it  follows  that  a  very  concentrated  syrup  must  not 
be  kept  in  a  place  where  the  temperature  is  likely  to  fall  much, 
otherwise  the  syrup,  having  deposited  the  excess  of  sugar,  which  it 
does  not  take  up  again  without  heating,  becomes  too  thin  and  may 
thus  readily  spoil. 
A  constant  or  prolonged  exposure  to  warmth  is  apt  to  be  detri- 
mental for  practically  the  same  reason  as  mentioned  above.  The 
warmth  makes  the  syrup  too  thin,  so  to  speak,  and  renders  it  sub- 
ject to  change. 
The  presence  of  easily  fermentable  substances  and  those  readily 
prone  to  decompose  cannot,  of  course,  be  avoided ;  hence  it  is  all 
the  more  important  that  due  regard  be  paid  to  the  quality  of  the 
syrup  used  in  order  not  to  increase  their  tendency  to  decompose, 
but  rather  to  prevent,  or  at  least  retard,  decomposition  as  much  as 
possible. 
Exposure  to  light  and  the  action  of  microbic  agents  are  also  easily 
avoided  or  prevented. 
We  now  come  to  what  is,  perhaps,  the  most  frequent  and  most 
mischievous  of  all  the  causes  from  which  syrups  spoil,  and  that  is  the 
impurities  in  the  sugar  from  which  the  syrup  is  made. 
Syrup  made  from  sugar  answering  the  requirements  of  the  U.S. P. 
is  a  very  stable  preparation,  if  of  proper  density.  Experience, 
