54  The  Metrical  System  in  Prescriptions.  {^•}™;S%rmt' 
to  measure  120  cubic  centimetres,  or  8  tablespoonfuls  ;  in  reality,  how- 
ever, it  will  be  found  to  measure  rather  more  than  123  cubic  centime- 
tres, an  excess  of  about  i\  per  cent,  over  the  expected  volume.  If" 
such  a  prescription,  without  the  signs  grm.  and  cc,  was  dispensed  by  a 
pharmacist  conversant  with  the  practice  of  continental  Europe,  it 
would  measure  a  little  over  108  cubic  centimetres,  a  deficiency  of 
per  cent,  of  the  expected  volume,  equal  to  a  difference  of  about  7  per 
cent,  between  the  variations -from  the  expected  measure,  the  combined 
difference  being  12J  per  cent.,  or  less  than  the  variation  in  the  approx- 
imate measure  of  the  tablespoonful,  which  is  usually  assumed  to  be  15 
cubic  centimetres  (about  half  a  fluidounce),  while  the  French  "Codex" 
gives  it  at  20  grams  (or  cubic  centimetres)  of  water,  a  difference  of  33; 
per  cent,  on  the  smaller,  and  of  25  per  cent,  on  the  larger  measure. 
In  this  connection  it  may  not  be  out  of  place  to  mention  some 
typographical  errors,  which,  however,  are  easily  recognized  as  such. 
In  Dr.  Blodgett's  paper,  as  published  in  both  journals  mentioned  above,, 
it  is  said  that  the  gram  equals  in  volume  16*2318  minims,  or  about 
"quarter  of  a  fluidounce";  this  should  read,  "quarter  of  a  fluid* 
drachm."  In  the  "  Proceedings  of  the  Amer.  Phar.  Assoc.,"  1876, 
p.  677,  the  writer  is  made  to  say  that  "  30  drachms  of  water  make  2 
tablespoonfuls,  and  40  drachms  of  syrup  about  the  same  measure," 
The  word  "  drachms,"  it  is  obvious,  should  read,  in  both  cases, 
"  grams." 
After  all  these  considerations,  it  must  be  quite  plain  to  the  physician 
and  pharmacist  that,  in  prescribing  by  metric  weights,  with  the  few 
simple  rules  advocated  in  my  previous  paper,  any  variation  between 
the  intended  and  the  actual  amount  of  even  a  potent  medicine  ordered 
must,  in  the  approximate  apportionment  of  doses  by  the  patient,  natu- 
rally fall  considerably  within  the  limits  of  the  variation  of  these  approx- 
imate measures  usually  employed  ;  and  that,  unless  maximum  doses  were 
directed,  in  which  case  it  would  be  the  special  duty  of  the  physician 
to  examine  the  approximate  measures  on  hand,  no  inconvenience  or 
danger  to  the  patient  could  result. 
In  the  above  I  have  alluded  only  to  the  practice  on  the  continent  of 
Europe  ;  how  is  it  upon  the  western  hemisphere  ?  A  paper  by  Prof. 
C.  G.  Wheeler,  of  Chicago,  presented  to  the  Amer.  Phar.  Assoc.  at 
its  last  meeting  (see  "Proceedings,"  1876,  p.  441)  throws  some  light 
upon  this,  and  we  learn,  in  the  countries  named  there  and  probably  upon 
