PRACTICAL  KNOWLEDGE. 
15 
theory  of  Dalton,  by  which  he  is  said  to  have  "  snatched  the 
science  from  the  chaos  of  indefinite  combination  and  bound  it 
in  the  chains  of  number."    He  will  also  have  felt  the  necessity 
of  a  more  familiar  acquaintance  with  chemical  symbols.  The 
next  step  of  the  process  is  the  preparation  of  the  requisite 
amount  of  quinia.    Here  it  will  be  necessary  for  him  to  calcu- 
late the  quantity  of  sulphate  of  quinia  that  will  yield  the  de- 
sired amount  of  the  alkaloid.    This  will  furnish  him  with  a 
practical  illustration  of  the  value  of  the  law  of  equivalent  com- 
bination, with  which  he  had  made  himself  familiar  during  the 
preceding  process.    The  extensive  subject  of  cinchona  will  natu- 
rally come  in  here  for  consideration,  and  if  a  knowledge  of  bot- 
any has  not  formed  a  part  of  his  education  hitherto  he  will, 
now  feel  the  want  of  it  most  keenly,  and  perhaps,  to  supply  this 
want,  he  will  be  induced  to  undertake  the  study  of  a  science  so 
pleasing  in  itself,  so  refreshing  in  its  influence,  and  withal  so 
fraught  with  usefulness  and  instruction.    The  quinia  having 
been  well  washed,  is  now  dissolved  in  the  filtered  solution  of 
citrate  of  iron,  evaporated  to  syrupy  consistence,  and  finally 
spread  on  plates  to  dry.    During  this  final  process,  he  may  be 
led  to  inquire  into  the  theory  of  evaporation,  the  various  methods 
of  conducting  it  according  to  the  objects  to  be  attained,  &c ;  he 
will  also  take  notice  that  the  salt  in  drying  assumes  no  definite 
form,  and  is  on  that  account  classed  as  an  amorphous  sub- 
stance ;  (in  connection  with  the  term  amorphous,  it  may  be  ob- 
served that  the  comprehension  and  easy  retention  of  the  mean- 
ing of  scientific  terms  is  greatly  facilitated  by  a  knowledge  of 
Latin  and  Greek  ;  and  if  the  operator  be  so  fortunate  as  to  have 
had  a  knowledge  of  these  languages  incorporated  into  his  early 
education,  he  has  reason  to  be  thankful).    The  process  is  now 
brought  successfully  to  its  close,  and  the  finished  product  lies 
before  him,  in  all  its  brilliancy  of  appearance,  delighting  his  eye 
and  exciting  within  him  a  feeling  of  pleased  satisfaction  at  the 
consciousness  of  its  being  the  result  of  his  own  labor  and  skill. 
The  writer  has  thus  endeavored  to  point  out  some  of  the  ad- 
vantages that  are  derived  from  the  manufacture  of  one  prepara- 
tion ;  there  are  many  others,  whose  preparation  is  equally  pro- 
ductive of  valuable  knowledge,  and  it  is  to  be  regretted  that  so 
few  apothecaries  take  advantage  of  this  cheap  and  easy  method 
