58  SACCHARINE  STRENGTH  OF  SYRUP  OF  IODIDE  OF  IRON. 
syrup  there  indicated,  we  should  find  that  it  would  be  necessary 
to  employ  13'33  ounces  by  weight,  Avoirdupois  (12*14  Troy,)  in 
place  of  the  10  ounces  present,  for  1*333  +  15  =  19*9  ounces  by 
weight,  or  13*33  sugar  +6*66  liquid  iodide  of  iron,  assuming  the 
specific  gravity  of  the  London  simple  syrup  to  be  similar  to  that 
of  the  Dublin,  which  it  is  very  nearly.  If  we  take  the  Edinburgh 
formula  to  represent  the  true  proportion  of  sugar  necessary,  the 
London  formula  should  be  represented  by  11*25  ounces  Troy,  in 
place  of  the  10  ounces  at  present  employed,  and  the  Dublin  by  6 
ounces  Troy  or  6*255  Avoirdupois,  in  place  of  5*33  ounces;  but 
in  this  there  is  a  deficiency  likewise,  as  the  4J  ounces  there  should 
be  more  correctly  represented  by  4*85  ounces,  or  something  better 
than  4 1  ounces  Troy. 
These  discrepancies  at  first  sight  appear  insignificant,  and  pro- 
bably unworthy  of  much  attention ;  however,  as  accuracy  should 
characterize  all  our  operations,  and  as  the  value  of  a  compound 
very  much  depends  on  it,  any  deviation  from  this  rule,  especially 
in  so  sensitive  a  preparation  as  iodide  of  iron,  seems  to  a  cer- 
tain extent  unwarrantable.  When  the  solution  of  iodide  of  iron 
is  treated  with  double  its  weight  of  sugar,  it  is  found  to  keep  ad- 
mirably well  for  a  considerable  period,  especially  when  protected 
from  the  air  and  light,  and  in  a  cool  situation,  taking  care  in  the 
fi:st  instance,  after  the  solution  of  the  sugar  is  effected,  to  bring 
it  near  its  boiling  point,  and  in  this  state  secluded  in  bottles 
perfectly  air-tight.  As  these  need  only  contain  from  two  to  three 
ounces  each,  and  can  be  conveniently  kept  in  stock,  there  will  be 
less  likelihood  of  their  contents  spoiling,  than  when  a  large  quan- 
tity of  the  syrup  is  kept  in  a  dispensing  bottle,  the  desultory 
opening  of  which,  from  time  to  time,  rapidly  produces  this  change. 
It  might  be  urged  that  the  amount  of  salt  it  contains  would  ne- 
cessarily dispose  it  to  crystallization,  with  the  above  amount  of 
sugar,  and  at  once  frustrate  the  object  of  its  conservation  ;  this, 
however,  will  be  found  not  the  case,  as  it  shows  no  symptom  of 
crystallization  under  the  circumstances,  at  least,  for  a  very  con- 
siderable time,  which  is  another  important  reason  for  employing 
this  quantity  of  sugar. 
The  following  formula  is  suggested  as  presenting  a  useful  inno- 
vation of  the  Dublin  process,  as  it  will  be  found,  owing  to  the 
omission  of  a  portion  of  the  manipulation  there  directed,  not  to 
