A%Jo°vU%87h7arm'}   Goa-powder  and  Chrysophanic  Acid.  547 
30°C,  and  in  224  parts  of  boiling  alcohol.  It  is  soluble  in  ether, 
glacial  acetic  acid,  amylic  alcohol,  and  in  alkaline  fluids.  In  benzole 
it  dissolves  freely,  and  this  menstruum  is  used  to  abstract  it  from  Goa- 
powder. 
Medical  Properties. — In  the  treatment  of  cutaneous  diseases,  such  as 
Tinea  circinata,  Tinea  tonsurans,  Mentagra,  etc.,  Goa-powder  has 
been  used  mixed  with  acetic  acid,  and  applied  with  a  brush  ;  or,  20  to 
80  grains  of  the  powder  are  mixed  with  10  grains  of  glacial  acetic  acid, 
and  incorporated  into  one  ounce  of  ointment. 
Dr.  Ashburton  Thompson  has  published  the  result  of  319  observa- 
tions made  upon  the  effects  of  the  internal  administration  of  Goa  and 
chrysophanic  acid.  As  a  summary  of  these  observations,  Dr.  Thomp- 
son finds  that  Goa  is  emetic  and  purgative — vomiting  is  usually  the  first 
action  unattended,  by  any  depression. 
Dose. — On  children  from  9  to  12  years  of  age,  6  grains  produce  no 
effect  ;  on  children  from  5  years  down  this  dose  is  sure  to  operate,  but 
the  time  of  action  may  vary  from  10  minutes  to  12  hours.  The  effect 
of  the  same  dose  is  not  increased  with  diminution  of  age.  With  adults 
a  dose  of  30  grains  operated  with  tolerable  uniformity  ;  the  interval 
elapsing  before  manifestation  of  effect  was  seldom  sooner  than  20  min- 
utes, and  may  be  as  long  as  5  hours. 
As  a  conclusion  to  these  extended  observations,  Dr.  Thompson  says 
that  "  Goa  (chrysarobin)  in  a  dose  of  20  to  25  grains  for  an  adult,  or  6 
or  more  grains  for  children,  is  an  emetic  purge,  unattended  by  any 
inconvenient  symptoms.  It  is  as  certain  as  other  medicines  which  act 
in  the  same  way." 
Chrysophanic  acid  in  a  suitable  dose  (15  to  20  grains)  will  cause  vom- 
iting and  purging  ;  if  the  dose  be  small,  it  will  vomit  only.  In  this 
action  it  is  the  reverse  of  Goa,  which  is  likely  to  purge  only  in  small 
doses.  For  children  of  10  years  or  under  6  grains  is  a  dose  ;  like  Goa, 
no  increase  of  effect  is  produced  on  younger  children  by  the  same  dose. 
On  children  of  less  than  4  or  5  years  its  action  is  more  uncertain  than 
Goa — it  fails  to  act,  acts  feebly,  or  vomits  only  ;  it  never  acts  with 
unexpected  violence.  With  adults  the  action  of  the  acid  is  pretty  cer- 
tain in  doses  of  15  grains.  Idiosyncrasies  require  an  adjustment  of  dose 
of  from  8  to  20  grains.  Whatever  the  condition  of  the  patient,  it 
causes  the  evacuation  in  one  way  or  the  other  of  large  quantities  of  bile. 
The  action  of  the  resin  of  Goa  (after  the  separation  of  the  chrysophanic 
