THE  AMERICAN 
JOURNAL  OF  PHARMACY.  X? 
-   \is 
SEPTEMBER,  i8qi.  + 
DIALYSIS  BY  MEANS  OF  SULPHATE  OF  CALCIUM. 
By  Guadalupe  Morales,  Ph.G.,  of  Nicaragua,  C.A. 
Contribution  from  the  Chemical  Laboratory  of  the  Philadelphia  College  of  Pharmacy.—  • 
No.  94. 
In  a  monograph  (See  Am.  Jour.  Pharmacy,  1889,  p.  159)  pub- 
lished by  Mr.  A.  L.  Herrera,  from  Mexico,  wherein  he  treats  of 
Chemical  Dialysis,  a  new  process  he  has  invented,  caused  me  to  try 
his  experiments,  following  his  instructions,  to  determine  if  that  pro- 
cess could  have  any  practical  application  for  the  extraction  of  alka- 
loids. 
He  says  that  it  has  not  been  studied  with  elaborate  care ;  what  he  has 
done  has  been  to  establish  the  general  principles,  corroborating  them 
with  a  certain  number  of  experiments,  done  with  several  substances 
under  different  conditions,  and  to  point  out  the  application  they  may 
have,  leaving  to  the  study  of  others,  who  may  want  to  try  them,  to 
determine  if  the  applications  which  he  indicates  can  have  any  prac- 
tical value;  he  declares  that  he  does  not  know  many  of  the  imper- 
fections and  objections  attached  to  his  process. 
In  order  to  understand  better  the  process  of  Mr.  Herrera,  I  will 
extract  and  condense  from  his  paper  the  more  important  points. 
"  When  water  or  an  aqueous  solution  is  separated  from  calcined 
sulphate  of  calcium  by  a  membrane  of  parchment  paper,  the  water 
passes  through  the  membrane  and  is  employed  in  the  hydration  of 
the  sulphates  ;  besides,  if  the  substances  in  solution  are  crystalloid, 
they  totally  pass  from  the  interior  to  the  exterior  of  the  dialyzator ; 
it  does  not  happen  thus  if  they  are  cclloid. 
(425) 
