266 
Sulpho-carholates. 
r  Am.  Jour.  Pharm 
1    June  1,  1871. 
removed,  the  remainder  placed  in  a  calico  cloth  and  strongly  pressed, 
by  which  a  farther  quantity  of  red  mother-liquor  is  got  rid  of,  leaving 
a  cake  of  sulpho-carbolate  nearly  pure  ;  this,  v/hen  again  dissolved, 
filtered  and  sufficiently  evaporated,  yields  the  salt  in  a  state  of  purity 
far  surpassing  any  other  sample  I  have  ever  seen.  As  the  expressed 
cake  is  so  nearly  pure,  almost  the  whole  of  it  may  be  recovered  by 
further  evaporation.  This  procedure  applies  equally  to  iron  and 
copper.  To  obtain  the  copper- salt,  the  diluted  acid  is  saturated  with 
freshly  prepai-ed  moist  carbonate  of  copper,  producing  a  beautiful 
intensely  green  solution,  which,  no  doubt  will  make  an  excellent 
color  for  druggists'  show-bottles.  The  crystals,  when  large,  are  a 
brilliant  blue,  and  form  clusters  of  great  beauty,  but  difficult  to  obtain, 
as  single  crystals  ;  when  small,  they  are  green,  probably  from  con- 
taining less  water  of  crystallization. 
The  iron  salt  was  obtained  by  the  action  of  the  acid  on  fine  iron 
wire  ;  the  color  of  the  crude  solution  is  a  most  intense  violet,  and, 
like  that  of  copper,  would  doubtless  make  a  good  color  for  show- 
bottles.  The  expressed  cake,  though  almost  v/hite,  when  dissolved, 
reproduces  the  characteristic  violet  in  almost  its  original  intensity  ; 
the  crystals  produced  from  this  solution  are  violet-green,  the  green 
predomin;iting ;  before  their  removal  from  the  evaporating  basin, 
they  should  be  carefully  washed  with  ice-cold  water  by  means  of  a 
syringe,  in  order  to  free  them  from  the  colored  mother-liquor  which 
adheres  with  great  pertinacity.  A  peculiarity  of  this  salt  is,  that  a 
freshly  prepared  solution  is  almost  colorless,  and  without  a  trace  of 
violet,  but  as  it  absorbs  oxygen,  peroxide  of  iron  is  precipitated,  the 
violet  tinge  once  more  appears,  and  increases  in  intensity  till  it  almost 
equals,  in  that  respect,  the  crude  solution. 
These  salts  are  all  easily  prepared,  are  very  stable,  and  as  they 
crystallize  from  pure  solutions  with  great  facility,  and  into  regular 
geometric  forms,  they  make  capital  show  objects.  Some  crystals  of 
the  calcium  salt  that  I  now  have  are  perfect  rhombs.  The  way  in 
which  all  these  solutions,  during  the  progress  of  crystallization,  climb 
up  and  over  the  sides  of  the  basin,  by  the  force  of  capillary  attraction, 
is  rather  astonishing,  unequalled,  as  far  as  ray  observation  goep,  by 
any  other  compound  ;  it  is  rather  a  nuisance,  but  may  be  completely 
prevented  by  slightly  greasing  the  inside  edge  of  the  vessel.  Into 
the  chemical  part  of  the  question  it  is  not  my  purpose  to  go,  but  the 
remarkable  changes  exhibited  by  some,  at  least,  of  the  sulpho-carbo- 
