VARIETIES. 
185 
able  sums  towards  the  restoration  of  some.  The  sulphuro-saline  springs 
of  Hamma  Mescoutin,  in  the  province  of  Constantine,  deserve  special  notice, 
not  onlj  from  their  efficacy,  but  from  the  fact  that  in  these  arsenic  was  first 
discovered;  the  consequence  was,  that  the  researches  of  Chemists  were  di- 
rected, in  analysing  mineral  waters,  to  the  presence  of  arsenic  as  a  conslit- 
uent,  and  that  this  mineral  has  been  lately  ascertained  to  exist  in  several 
of  our  European  springs,  such  as  Montdore  and  many  others. — London 
Pharm.  Jour. 
On  Writing  Inks.  By  James  Stark,  M.  D.,  F.  R.  S.  E  — The  author 
stated  that  in  1842,  he  had  commenced  a  series  of  experiments  in  writing 
inks,  and  up  to  this  date  had  manufactured  229  different  inks,  and  tested 
the  durability  of  writings  made  with  these  on  all  kinds  of  paper.  As  the 
result  of  his  experiments,  he  showed  thatthe  browning  and  fading  of  inks  re- 
sulted from  many  causes,  but  in  ordinary  inks  chiefly  from  the  iron  becoming 
peroxygenated,  and  separating  as  a  heavy  precipitate.  Many  inks,  there- 
fore, when  fresh  made,  yielded  durable  writings  ;  but  when  the  ink  became 
old,  the  tannogallate  of  iron  separated,  and  the  durability  of  the  ink  was 
destroyed.  From  a  numerous  series  of  experiments,  the  author  showed 
that  no  salt  of  iron  and  no  preparation  of  iron  equalled  the  common  sul- 
phate of  iron,  that  is,  the  commercial  copperas,  for  the  purposes  of  ink- 
making,  and  that  even  the  addition  of  any  persalt,  such  as  the  nitrate  or 
chloride  of  iron,  though  it  improved  the  present  color  of  the  ink,  deteriora- 
ted its  durability.  The  author  failed  to  procure  a  persistent  black  ink, 
from  manganese  or  other  metal  or  metallic  salt.  The  author  exhibited  a 
series  of  eighteen  inks,  which  had  either  been  made  with  metallic  iron,  or 
with  which  metallic  iron  had  been  immersed,  and  directed  attention  to  the 
fact  that,  though  the  depth  and  body  of  color  seemed  to  be  deepened,  yet 
in  every  case  the  durability  of  writings  made  with  such  ink  was  so  impaired, 
that  they  become  brown  and  faded  in  a  few  months.  The  most  permanent 
ordinary  inks,  where  shown  to  bo  composed  of  the  best  blue  gall-nuts  with 
copperas  and  gum,  and  the  proportions  found  on  experiment  to  yield  the 
most  persistent  black,  were  six  parts  of  best  blue-galls  to  four  parts  of 
copperas.  Writings  made  with  such  an  ink,  stood  exposure  to  sun  and 
air  for  twelve  months,  without  exhibiting  any  change  of  color,  while  those 
made  with  inks  of  every  other  proportion  or  composition  had  more  or  less 
of  their  color  discharged  when  similarly  tested.  This  ink,  therefore,  if  kept 
from  moulding  and  depositing  its  tannogallate  of  iron,  would  afford  wri- 
tings perfectly  durable.  It  was  shown  that  no  gall  and  logwood  ink  was 
equal  to  the  pure  gall  ink,  in  so  far  as  durability  in  the  writings  was  con- 
cerned. All  such  inks  lost  their  color  and  faded  sooner  than  pure  gall 
inks,  and  several  inks  were  exhibited,  which,  though  durable  before  the  ad- 
dition of  logwood,  faded  rapidly  after  logwood  was  added  to  them.  Sugar 
was  shown  to  have  an  especially  hurtful  action  on  the  durability  of  inks 
