Method  of  tanning  Leather.  129 
entirely  ufelefs ; for  which  purpofe  you  muft  contrive  a 
gutter  in  the  tan-yard  to  carry  off  the  fpent  ooze. 
xxvi.  The  letches  ought  to  be  under  cover,  left  the 
rain  get  into  them  and  weaken  the  ooze,  and  if  the 
handlers  are  fheltered,  it  will  be  fo  much  the  better;  but 
/ 
it  is  of  no  importance  to  cover  the  vatts,  provided,  when 
the  leather  is  laid  away  in  them,  they  are  kept  conftantly 
full  to  the  brim. 
xxvii.  You  muft  always  take  care  to  have  a fufficient 
ftock  of  unflaked  lime  by  you  (for  if  it  be  flaked,  it  will 
not  anfwer  to  make  lime-water):  therefore,  get  your 
lime  frefh,  if  poflible,  from  the  kiln,  and  immediately 
pack  it  in  any  kind  of  old  dry  calks.  Weigh  one  of  thefe 
calks,  and  it  will  enable  you  to  afcertain  the  quantity  of 
lime  neceflary  to  be  thrown  into  the  ciftern  each  time 
you  begin  a frelh  brewing  of  your  lime-water,  and 
thus  fave  you  the  trouble  of  repeated  weighings ; not 
that  there  need  be  much  nicety  about  the  quantity  of 
lime,  a fcore  of  pounds  over  or  under  making  no  fenfible 
difference  in  the  ftrength  of  the  lime-water. 
xxvni.  Any  expence  you  may  be  at  in  procuring 
lime,  which  even  in  the  largeft  tan-yards  can  amount 
but  to  a trifle,  will  be  amply  compenfated  by  the  faving 
of  bark;  becaufe,  that  lime-water  fo  completely  exhaufts 
Vol.  LXVIII.  S the 
