ON  SOLUTIO  ATROPI^  GLYCERINEA. 
65 
with  a  view  to  its  use  as  an  elegant  and  efficient  mode  of  ex- 
hibiting this  substance  where  permanent  dilatation  of  the  pupil  is 
requisite.  A  saturated  solution  in  glycerine  gave  on  analysis 
four  per  cent.  (=:gr.  xvijss.  ad.  gi.)  of  the  vegeto-alkali.  It 
does  not  dissolve  readily  in  the  cold,  but  is  soluble  almost  to  any 
extent  on  applying  a  gentle  heat ;  the  excess,  if  it  is  not  great, 
deposits  on  cooling  in  fine  transparent  colorless  prisms,  but  if 
the  amount  is  considerable  it  becomes  when  cool  a  solid  mass. 
From  this  it  is  evident  its  solubility  in  glycerine  is  much  greater 
than  in  water,  it  requiring  189  parts  of  the  latter  menstruum  to 
dissolve  it  in  the  cold  ;*  indeed  the  atropia  is  recoverable  to  a 
considerable  extent  by  precipitation  on  the  addition  of  water  to 
the  glycerolic  solution.  The  easiest  method  of  making  this 
solution  is  as  follows: — One  decigramme  (=1-543  grains)  dis- 
solved in  a  few  drops  of  alcohol  is  added  to  20  grammes 
(=:  368-680  grains)  of  distilled  glycerine;  the  mixture  is  then 
subjected  to  a  gentle  heat,  viz.  about  110°  F.  for  half  an  hour 
in  an  evaporating  capsule  to  volatilize  the  spirit.  This  will  con- 
tain one  half  per  cent.  i.  e,  2-187  grains  to  the  ounce,  and~may  be 
labelled  "  Fortior."  On  smearing  the  surrounding  parts  of  his 
eye  the  writer  found  (without  dropping  in  any  solution)  the 
dilation  of  the  pupil  perceptible  in  15  minutes,  from  which  time 
it  steadily  increased.  A  weaker  solution^  i.  e.  one  containing 
one-fourth  per  cent,  made  by  using  one  decigramme,  to  40 
grammes,  may  be  used  to  determine  the  dilatation,  by  an  un- 
occasional  application,  and  also  to  allow  for  absorption.  A  solu- 
tion in  glycerine  of  atropia  may  be  made  contain  16  grains  to 
the  ounce,  without  any  danger  of  its  crystallising  out. 
The  advantages  to  be  derived  from  the  use  of  this  prepara- 
tion, are,  first,  the  emollient  properties  of  the  glycerine,  which 
by  softening  and  relaxing  the  scarfskin,  freely  allows  the  ab- 
*  The  author  was  induced  to  enter  into  the  examination  of  the  solu- 
bility in  water  from  observing  the  non-conformity  of  works  of  reference  on 
this  subject.  His  experiments  gave  as  a  mean  result  1  part  atropia,  to  be 
soluble  in  189,  generally  given  as  soluble  in  300  parts,  whilst  Lowig  gives 
it  as  requiring  2000  ;  the  writer  thinks  this  must  be  a  typographical  error 
and  must  be  intended  for  200  parts.  This  diversity  might  be  accounted 
forinsome  degree;  as  an  amorphous  modification,  produced  by  the  action 
of  a  gentle  heat,  is  apparently  much  more  soluble.  This  uncrystallisable 
variety  is  equally  efficient  with  the  other  in  dilating  the  pupil. 
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