SULPHUR  IN  OIL  OF  VITRIOL  Oil  SULPHURIC  ACID.  431 
ON  THE  SOURCES  OF  SULPHUR  USED  IN  THE  MANUFAC- 
TURE OF  OIL  OF  VITROL  OR  SULPHURIC  ACID. 
By  James  Mactear,  F.C.S. 
Of  the  Alkali  Department,  St.  Rollox  Chemical  Works. 
After  making  some  few  preliminary  remarks,  Mr.  Mactear  pro- 
ceeded to  say  that  the  quantity  of  oil  of  vitrol  manufactured  in  this 
country  exceeds  500,000  tons  per  annum,  and  of  this  quantity 
about  320,000  tons  are  used  in  the  conversion  of  common  salt 
into  sulphate  of  soda,  for  the  production  of  alkali  by  Leblanc's 
process,  the  remainder  being  taken  up  chiefly  in  the  manufacture 
of  artificial  manures.  The  sulphur  consumed  last  year,  in 
making  oil  of  vitrol,  amounted  to  160,000  tons,  but  of  this 
quantity  only  from  10,000  to  20,000  tons  consisted  of  brimstone  ; 
the  remainder  is  obtained  from  pyrites,  of  which  upwards  of 
375,000  tons  were  burned.  The  brimstone  is  used  chiefly  in  the 
manufacture  of  "  sale  acid,"  and  this  again  is  used  mostly  for 
bleaching  purposes,  which  require  a  very  pure  acid,  that  made 
from  pyrites  being  always  more  or  less  contaminated  with 
arsenic  and  other  impurities  of  a  detrimental  character. 
Since  the  year  1851  the  price  of  brimstone  has  been  very 
high,  owing  to  the  great  quantity  of  sulphur  required  in  the 
treatment  of  the  vine  disease. 
Up  to  the  year  1856  all  the  pyrites  used  was  obtained 
from  Cornwall  and  Ireland,  except  a  small  quantity  of  "  coal 
brasses  "  found  in  the  coal-fields.  In  that  year  some  cargos  of 
Spanish  pyrites,  containing  a  small  per-centage  of  copper,  were 
imported  and  used  by  the  Tyne  manufacturers,  who  liked  the 
ore  very  much,  on  account  of  the  high  percentage  of  sulphur 
which  it  contained  ;  while  it  is  burned  at  as  low  a  cost  per  ton 
as  the  ore  of  low  strength.  At  least  one  half  of  the  ore  now 
used  is  Spanish  cupriferous  pyrites.  The  author  illustrated  the 
economy  of  working  pyrites  by  stating  that  Irish  ore  contains 
about  35  per  cent,  of  sulphur,  while  Spanish  ore  contains  as 
much  as  from  45  to  50  per  cent.  ;  and,  assuming  that  the  cost 
of  burning  in  both  cases  is  2s.  per  ton,  in  the  one  case  35  parts, 
and  in  the  other  from  45  to  50,  are  burned  off  for  the  same 
amount.    But  it  is  found  that  the  refuse  contains,  in  both  cases. 
