ADecimberi™'}  Metric  Medicine  Glass.  591 
quantities  until  they  have  converted  them  into  the  more  familiar 
system  of  ounces  and  pounds.  For  example,  200  c.c.  represents 
nothing  tangible  to  the  average  mind  until  the  person  has  converted 
this  term  into  the  approximate  equivalent  of  six  and  three-quarter 
ounces.  In  other  words,  we  have  not  as  yet  accustomed  ourselves  to 
think  in  decimal  quantities,  but  continue  to  think  of  and  to  figure 
out  quantities  in  ounces  and  fractions  and  subsequently  attempt  to 
transpose  them  into  their  metric  equivalents.  This  process  is  not 
only  tedious;  it  is  also  uncertain  and,  to  a  certain  extent,  dangerous, 
as  a  person  who  must  necessarily  transpose  from  one  system  to 
another  cannot  have  an  exact  knowledge  of  the  approximate  values 
of  weights  and  measures  of  the  system  that  he  is  transposing  into. 
This  is  a  point  that  should  not  be  lost  sight  of,  and  especially  in 
the  metric  system,  where  the  simple  displacement  of  a  figure  means 
the  mistake  of  ten  or  a  multiple  of  ten. 
But  even  in  cases  where  an  actual  and  sincere  attempt  has  been 
made  to  use  the  metric  system  in  the  prescribing  and  dispensing  of 
medicines,  we  have  an  impediment  in  the  accepted  approximate- 
values  of  capacities  assigned  to  the  various  household  utensils  that 
are  commonly  used  to  measure  out  doses  of  liquid  medicines.  Thus, 
for  instance,  custom  has  sanctioned  the  practice  of  accepting  the 
capacity  of  a  teaspoon  to  be  a  fluid  drachm,  and  a  tablespoon  to  be 
equal  in  capacity  to  four  teaspoons,  or  to  hold  approximately  half  a 
fluid  ounce.  Now,  any  one  who  is  sufficiently  interested  can  readily 
prove  to  himself  that  not  only  do  the  various  spoons  differ  consider- 
ably in  their  actual  capacity,  but  that  the  average  capacity  of  an 
ordinary  teaspoon  is  much  greater  than  that  usually  assigned  to  it. 
You  will  also  find  that  but  few  tablespoons  will  hold  more  than  the 
equivalent  of  three  teaspoons. 
It  is  true  that  in  many  cases  a  glass  medicine  glass  or  tumbler 
has  displaced  the  more  domestic  method  of  measuring  with  the 
actual  spoon,  and  that  by  this  means  we  are  able  to  give  more  evenly 
divided  doses ;  still,  even  our  glass  medicine  tumblers  do  not  always 
hold  the  exact  quantities  that  the  graduations  would  indicate,  and 
in  others  where  the  graduations  are  correct  the  tumblers  are  of  such 
a  shape  that  absolutely  accurate  results  would  be  difficult  to  obtain, 
even  by  an  expert. 
But  what  we  wish  to  call  particular  attention  to  is  the  fact  that  in 
transposing  these  approximate  capacities  into  their  metric  equiva- 
