PRACTICAL  KNOWLEDGE. 
18 
but  must  increase  his  knowledge.  In  no  way  can  he  more 
surely  do  this  than  by  engaging  in  the  actual  preparation  of 
the  medicines  he  dispenses.  Here  his  former  stores  of  know- 
ledge are  called  into  requisition — facts,  long  forgotten,  transpire 
before  his  eye,  and  this  time  fix  themselves  on  his  memory  not 
soon  again  to  be  forgotten ;  new  phenomena  are  observed  and 
treasured  in  the  mind — food  for  future  thought ;  the  laws  of 
chemical  science  are  seen  silently  but  surely  at  work,  effecting 
their  wonderful  and  oftentimes  exceedingly  beautiful  changes 
and  combinations,  thus  at  the  same  time  affording  pleasure  to 
the  eye  and  instruction  to  the  mind.  It  is  admitted  that  many 
of  these  preparations  can  be  bought,  ready  made,'  of  the  manu- 
facturing chemist  and  pharmaceutist,  of  good  quality,  and  at  a 
price  not  much  exceeding  what  it  would  cost  the  apothecary  to 
make  them  for  himself;  but  it  is  maintained,  nevertheless,  that  the 
apothecary  who  makes  them  for  himself  will  be  richly  repaid  in 
the  abundant  stores  of  real  practical  knowledge  which  he  will 
gather  from  this  source ;  and  it  is  to  be  remembered  that,  to  the 
apothecary,  knowledge  is  money.  The  preparation  of  citrate  of 
iron  and  quinia  affords  a  good  illustration  of  the  amount  of 
practical  knowledge  that  may  be  gained  in  this  way.  Having, 
first  of  all,  carefully  studied  the  formula  with  the  remarks  ap- 
pended thereto,  the  operator  proceeds  with  the  first  step  of  the 
process — the  preparation  of  the  sulphate  of  iron.  The  sulphu- 
ric acid,  iron  and  water,  being  put  together  and  left  to  them- 
selves, he  will  in  the  mean  time  have  recourse  to  his  Dispensatory, 
and  thence  acquaint  himself  with  the  nature  of  the  reactions 
taking  place,  the  various  methods  of  manufacturing  the  salt,  its 
chemical  constitution,  tests  of  purity,  medical  properties,  &c. 
All  reaction  having  ceased,  the  liquid  is  filtered  and  further 
treated,  according  to  the  directions  of  the  formula,  till  finally  is 
obtained  a  mass  of  beautiful  bluish-green  crystals  of  pure  sul- 
phate of  protoxide  of  iron.  In  this  process,  particularly  if  he 
has  followed  that  of  the  U.  S.  P.,  he  will  have  had  his  attention  di- 
rected to  the  great  tendency  of  protosalts  of  iron,  to  absorb 
oxygen  from  the  atmosphere,  and  consequently  to  the  necessity 
of  protecting  them  from  its  influence,  as  much  as  possible,  in  all 
those  preparations  wherein  a  pure  protosalt  is  desired.  He 
will  also  have  witnessed  the  interesting  process  of  crystallization, 
