Am'Mryri884arm'}        Alcohol  Tables  of  Hehner  and  Pile.  255 
obtained  by  carefully  following  out  the  ordinary  plan  of  dehydrating 
by  means  of  quick  lime. 
If  this  is  true,  the  tables  are  fairly  turned  on  Mr.  Pile,  for  it  is 
his  table,  and  not  that  of  Hehner,  which  (practically)  adopts  "  two 
different  values  to  denote  the  specific  gravity  of  water  as  a  standard, 
one  at  the  beginning  and  another  at  the  end."  We  hasten  to  explain, 
however,  that  such  a  change  of  standard  does  not,  after  all,  seriously 
affect  the  figures  in  the  important  portions  of  the  table,  and  further, 
that  all  the  alcohol  tables  in  common  use,  except  that  of  Fownes-' 
Hehner,  are  open  to  criticism  of  the  same  kind. 
Mr.  Pile  seems  to  regard .  the  standard  of  pure  alcohol,  like  that  of 
a  unit  of  weight  or  measure,  as  something  dependent  on  conventional 
or  legal  definition.  He  says  "  alcohol  having  a  specific  gravity  of 
*8157  has  been  regarded  as  95  per  cent,  alcohol  for  so  long  a  time  that 
it  would  seem  to  be  difficult  to  interpret  it  in  any  other  way,  but  by 
the  adoption  of  the  tables  of  Hehner  it  will  have  a  specific  gravity  of 
*8161,  and  so  on."  And  again,  "why  not  compile  tables  having 
Tralles  as  a  basis,  and  thus  keep  in  harmony  with  law  and  custom?" 
This  evidently,  would  make  the  scientific  correctness  of  an  alcoholometri- 
cal  table  of  no  importance,  and  its  whole  value  conventional.  We  must 
here  take  issue  with  him,  taking  the  ground  that  no  conventions  can 
alter  mathematical  relations,  or  properties  inherent  in  chemical  com- 
pounds. The  object  of  tables  such  as  these  is  to  furnish  not  only  a 
uniform,  but  also  a  correct  basis  for  the  valuation  of  alcoholic  liquors 
in  commercial  transactions,  and  a  scientific  truth  is  the  only  ground  on 
which  the  figures  of  such  a  table  can  be  criticized. 
The  question,  therefore,  between  Tralles  and  Fownes,  between  Pile 
and  Hehner,  is  wholly  one  for  the  experimental  physicist  to  decide. 
I  have  myself  examined  somewhat  closely  the  subject,  and  am  con- 
vinced, not  on  a  priori  grounds,  but  from  crucial  experiments,  that 
Tralles  is  more  nearly  correct  in  the  main  in  his  figures  than  Fownes, 
and  hence  I  am  glad  that  Mr.  Pile  has  expended  so  much  careful 
labor  in  expanding  them,  since  Hehner  had  previously  done  the  same 
service  for  the  less  worthy  table  of  Fownes.  I  only  regret  that  he  did 
not  go  quite  to  the  root  of  the  matter,  and  furnish  us  with  an  original 
table  more  correct  than  either. 
Fownes'  table  was  adopted  some  years  ago  by  Dr.  Squibb  as  a  basis, 
in  part,  of  his  very  elaborate  and  valuable  alcohol  tables.  His  figures 
were  placed  side  by  side  in  those  tables  with  those  of  Tralles,  with  no 
