What  is  Terra  Alba? 
{  Am.  Jour.  Pharm. 
\    February,  1913. 
Nevada,  New  Hampshire,  New  Jersey,  New  York,  North  Carolina, 
North  Dakota,  Ohio,  Oklahoma,  Oregon,  Rhode  Island,  South 
Carolina,  South  Dakota,  Tennessee,  Texas,  Utah,  Vermont, 
Virginia,  Washington  and  Wyoming.  No  interpretation  of  this 
clause  or  ruling  in  which  these  substances  are  specifically  defined 
could  be  found  in  any  of  the  foregoing  instances. 
One  would  naturally  suppose  that  the  identity  of  a  substance 
which  is  referred  to  by  name  in  so  many  laws  could  be  easily 
established  by  referring  to  chemical  authorities  or  general  works 
of  reference,  but  such  is  not  the  case. 
I  recently  had  the  question  put  to  me  directly  "  What  is  terra 
alba  ?  "  and  having  answered  it  in  my  own  mind,  off  hand,  as  being 
powdered  gypsum,  I  set  about  confirming  this  opinion  and  soon 
found  it  no  easy  task,  for  not  only  did  I  find  that  a  large  number 
of  authorities  make  no  mention  at  all  of  the  substance  in  their 
indexes,  but  I  found,  what  was  still  more  disconcerting,  that  those 
who  did  mention  it  and  attempted  to  define  it,  did  not  agree  as 
to  its  identity. 
The  first  authority  I  turned  to  was  Wiley,  "  Foods  and  Their 
Adulteration,"  1906,  where  it  is  defined  as  being  talc.  This  is  the 
only  authority  of  the  many  consulted  by  whom  talc  is  mentioned  as 
a  synonym  for  terra  alba  and  this  is  probably  an  error  or  the  two 
substances  would  not  be  mentioned  separately  in  the  clause  quoted 
from  the  Federal  Act. 
The  Century  Dictionary  (1906  and  1912)  gives  pipe  clay  as  a 
synonym.  This  same  statement  is  made  in  Gould's  Medical 
Dictionary,  1908,  in  the  Standard  Dictionary,  1902,  and  in  Lippin- 
cott's  Medical  Dictionary  (Cattell),  19 10.  White  clay  is  the 
synonym  given  in  Dorland's  American  Illustrated  Medical  Diction- 
ary, 1906,  and  in  the  National  Dispensatory,  1908. 
Gypsum  is  given  as  the  synonym  for  terra  alba  in  Thorpe's 
Outlines  of  Industrial  Chemistry,  in  Allen's  Commercial  Organic 
Analysis,  Vol.  I,  under  Paper,  1910,  in  Bartley's  Medical  Chemistry, 
1900,  and  in  Witthaus'  Chemistry,  1890. 
In  Kraemer's  Pharmacognosy,  19 10,  the  statement  is  made  that 
terra  alba  is  a  compound  of  alumina,  silica  and  magnesia.  Merck's 
Index  for  1907  (a  price  list)  gives  kaolin  as  being  identical  with 
terra  alba. 
In  the  hope  that  some  light  might  be  shed  upon  the  subject  in 
