254  'Alcohol  Tables  of  Hehner  and  Pile.  {AmMaTi884arm" 
of  one-tenth  to  one-fortieth  of  one  per  cent,  we  ought  not  to  expect 
any  such  large  margin. 
According  to  Hehner  (Fownes)  the  specific  gravity  of  absolute  alco- 
hol is  "7938;  according  to  Pile  (Trail es)  it  is  '7939.  Were  the  same 
unit  adopted  by  the  two  authorities,  these  figures  might  be  considered 
practically  identical,  but  in  fact  the  difference  is  '0008,  amounting  to 
nearly  one  quarter  of  one  per  cent.  Mr.  Pile  deliberately  adopts  his 
value  as  established  beyond  question,  quoting  a  legal  enactment  of  the 
United  States  as  authority,  which  places  the  matter  beyond  dispute. 
He  says  :  "  Hehner  began  his  tables  by  denoting  the  specific  gravity  of 
water  as  1*000  at  60°  F.,  but  at  the  end  of  his  table,  we  find  absolute 
alcohol  indicated  by  a  specific  gravity  of  '7938,  which  is  the  case  when 
compared  with  water  as  unity  at  39°  F.,  but  when  water  is  taken  as 
unity  at  60° F.,  as  he  began  it  should  be  represented  by  "7946."  This 
is  pure  assumption,  and  as  we  shall  presently  see  is  not  correct,  but  to  the 
author's  mind  the  proposition  is  one  capable  of  easy  demonstration.  A 
United  States  statute  has  established  beyond  controversy  the  true 
specific  gravity  of  absolute  alcohol.  The  following  is  the  language  of 
the  statute  :  "  Proof  spirit  shall  be  held  and  taken  to  be  that  alcoholic  /j 
liquor  which  shall  contain  one-half  its  volume  of  alcohol  of  a  specific 
gravity  of  '7939  at  60°  F.  referred  to  water  at  its  maximum  density 
as  unity."  The  statute  is  unfortunate  in  its  wording,  inasmuch  as  it 
does  not  specify  at  what  temperature  the  liquid  shall  be  measured,  and 
it  only  implies  that  the  "alcohol"  described  is  an  anhydrous  spirit. 
The  law7  defines  what,  legally,  shall  be  called  proof  spirit ;  it  does  not 
fix  the  physical  properties  of  the  chemical  compound,  ethylic  alcohol. 
That  is  something  to  be  determined  by  actual  observation  :  the  law  by 
which  it  was  fixed  is  not  written  in  any  human  statute  book. 
Dr.  Squibb  states  that  he  has  observed,  repeatedly,  in  samples  of 
absolute  alcohol  a  specific  gravity  as  low  as  '7934  at  60°F.,  water  at 
the  same  temperature  being  taken  as  standard.  I  do  not  find  that  any 
other  observer  confirms  this  statement ;  if  it  is  true,  none  of  our  alco- 
hol tables  are  quite  correct,  but  that  of  Fownes,  adopting  the  figure 
of  Drinkwrater  ('79383),  is  in  this  particular  nearest  to  the  truth.  I 
have  not  been  able  to  confirm  Dr.  Squibb's  statement,  but  I  have 
never  been  satisfied  that  alcohol  was  completely  dehydrated  until  its 
specific  gravity  was  reduced  to '79385  at  60°F.,  water  at  the  same 
temperature  being  standard,  and  a  spirit  of  that  strength  can  easily  be 
