AmMay,ri884arm'}        Alcohol  Tables  of  Hehner  and  Pile.  253 
safe  to  say  that  they  are  nearly  perfect  in  this  regard.  In  the  table  of 
the  Pharmacopoeia,  several  misprints  have  escaped  correction.  I  note 
the  following:  corresponding  with  sp.gr.  "9180,  vol.  per  cent.,  58*92 
should  be  57*92  ;  sp.  gr.  -8215,  vol.  per  cent.  83*62  should  read  93*62  ; 
sp.  gr.  *8161,  vol.  per  cent.  94*00  should  read  95*00.  But  the  error 
in  each  case  is  so  obvious  that  it  could  rarely  occasion  mistake. 
Pile  distinctly  states  that  he  bases  his  table  upon  that  of  Tralles.  It 
is  easy  to  see  that  Hehner's,  on  the  other  hand,  is  merely  an  amplifi- 
cation of  that  of  Fownes,  with  a  few  unimportant  variations.  The 
figures  of  the  two  tables  differ  materially,  but  not  by  any  means  so 
greatly  as  would  appear  from  the  tabulated  comparison  given  by  Mr. 
Pile  ("Jour,  of  Pharmacy/'  February  1884,  page  71).  From  these 
figures  there  would  seem  to  be  a  difference  between  them  amounting 
in  some  cases  to  more  than  one  per  cent.  But  it  must  be  remembered 
that  Hehner's  table  takes  water  at  60°  F.  as  unity,  while  in  Tralles' 
table,  water  at  its  maximum  density  is  the  standard  adopted.  Reducing 
the  figures  to  a  common  standard,  we  shall  find  that  the  maximum 
difference,  does  not  exceed  one-fourth  of  one  per  cent.  The  corrected 
figures  are  as  follows  : 
Specific  Gravity. 
Trall.es. 
Hehner. 
Weight. 
Volume. 
Weight. 
Volume. 
•9991 
o-oo 
o-oo 
o-oo 
o-oo 
•9857 
8-05 
10  -oo 
8-22 
10-22 
•9751 
16-29 
20  -00 
16-47 
20-25 
•9646 
•    24  -69 
30-00 
24-78 
30-14 
•9510 
33-39 
40-00 
33-55 
40-23 
•9335 
42*52 
50-00 
42  -60 
50  14 
•9126 
52-19 
60-00 
52*04 
59-88 
•8892 
62  -50 
70-00 
62-36 
69-92 
•8631 
73-59 
80-00 
73-43 
79-91 
•8332 
85-75 
90*00 
85-67 
90-01 
•7939 
100-00 
100  -oo 
99-73 
99  83 
Carrying  the  comparison  through  the  whole  of  the  two  tables,  I  find 
the  range  of  variation  hardly  greater  than  it  appears  in  these  selected 
figures.  Such  a  variation,  for  ordinary  purposes,  is  not  of  very  great 
importance,  although  in  tables  which  profess  to  discriminate  differences 
