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ON  SULPHATE  05  ALUMINA  AND  ITS  USE. 
cant  and  evaporate  again,  is  too  long  and  disagreeable  a  task 
to  be  preferred  to  the  purification  with  muriatic  acid  ;  this  last 
method,  perhaps,  has  another  advantage,  to  evaporate  the  nitrous 
acid  present  in  most  commercial  sulphuric  acid  as  chloride  of 
oxide  of  nitrogen. 
ON  SULPHATE  OF  ALUMINA  AND  ITS  USE. 
By  Prof.  Dr.  Waltl. 
[Translated  from  Buchner's  N.  Repertorium,  1855,  p.  1.    By  J.  M.  Maisch.] 
Sulphate  of  alumina  is  one  of  the  most  useful  salts  of  all  those 
that  have  recently  come  into  technical  use.  It  is  often  prepared 
in  large  quantities  in  chemical  factories,  for  the  use  of  paper 
and  Prussian  blue  manufactories  ;  its  price  is  low,  it  is  unchange- 
able in  the  air,  and  contains  25  per  cent,  of  alumina,  which  makes 
it  much  cheaper  than  alum,  that  contains  but  one  half  of  it. 
Chemically  spoken,  it  may  be  viewed  as  alum  without  potassa  or 
oxide  of  ammonia,  which  are  replaced  by  alumina. 
Although  it  has  long  since  been  known  that  sulphate  of  alumina 
separates  both  the  above  bases  from  even  mineral  acids,  for  which 
reason  chloride  of  potassium  is  used  in  manufacturing  alum,  still 
nobody  has  thought  of  it  yet,  to  separate  in  this  way  tartaric 
acid  and  potassa  of  cream  of  tartar,  thus  to  find  a  new  way  for 
making  tartaric  acid. 
Is  oz.  sulphate  of  alumina  dissolved  in  1  lb.  water  with  the 
addition  of  about  I  oz.  sulphuric  acid,  necessary  to  form  the 
double  sulphate  (alum),  decompose  1  oz.  of  cream  of  tartar,  by 
digestion  without  boiling  ;  after  a  slow  evaporation  this  will  yield 
on  cooling  2  oz.  alum  in  large  crystals,  free  of  iron,  and  all  the 
tartaric  acid  which  may  be  obtained  in  crystals  by  a  very  slow 
evaporation.  I  recommend  this  new  mode  of  obtaining  tartaric 
acid  to  all  manufacturers ;  it  is  much  cheaper  than  the  old  way, 
which  requires  so  much  room,  heat  and  time. 
By  means  of  the  sulphate  of  alumina,  the  amount  of  potassa  in 
table  salt,  Glauber's  salts,  cubic  nitre,  and  in  the  mother  liquors 
of  sea  water  and  saline  brines,  may  be  detected,  and  the  allega- 
tion is  not  so  improbable  as  at  first  it  may  seem  to  be,  that  in 
a  future  time  we  may  obtain  from  the  waters  of  the  sea,  an  article 
for  the  production  of  which  we  have  at  present  to  look  to  the 
