n6  Dr.  macbride’s  Unproved 
cutting  out  a bit  of  the  thickefi:  part  of  the  hide)  the 
manufacture  is  finiflied,  fo  far  as  relates  to  tanning,  lince 
nothing  now  remains  but  to  dry  the  goods  thoroughly, 
by  hanging  them  up  in  airy  lofts  built  for  the  purpofe. 
Such  in'general  is  the  procefs  for  tanning  calf-fkins,  and 
thofe  lighter  forts  of  hides  which  are  called  butts ; but 
the  large,  thick,  heavy  hides,  of  which  the  ftrongeft  and 
moft  durable  kind  of  foal-leather  is  made,  require  to 
have  their  pores  more  thoroughly  opened  before  the 
ooze  can  fufficiently  penetrate  them.  For  this  purpofe, 
while  the  hides  are  in  the  putrefcent  ftate,  from  being 
allowed  to  heat  in  the  manner  already  mentioned,  and 
well  foaked  in  an  alcaline  ley,  they  are  thrown  into  a four 
liquor,  generally  brewed  from  rye,  in  order  that  the 
effervefcence  which  neceflarily  enfues  may  open  the 
pores. 
The  tanners  term  this  operation  railing,  as  the  lea- 
ther is  conliderably  fwelled,  in  coniequence  of  the  con- 
flict between  the  acid  and  alcali.  This  is  an  Englifh 
invention;  for  it  appears  from  M.  de  la  lande,  who 
was  employed  by  the  Royal  Academy  of  Sciences  to 
write  on  the  art  of  tanning,  that  the  foreign  tanners 
know  nothing  of  this  branch  of  the  bufinefs:  indeed, 
their  whole  procefs,  according  to  his  account,  is  flovenly, 
and 
