Am'\J?iir'i9?9rm'  }       Thc  Pharmaceutical  Chemist. 
227 
amount  of  insoluble  matter.  The  best  thing  available  was  one  par- 
ticular grade  of  resistant  enamel,  though  had  it  been  available  on  a 
commercial  scale,  a  pure  silver  pan  would  probably  have  been  just 
as  effective. 
When  it  comes  to  milk  sugar  or  alkaloidal  salts,  it  would  seem 
that  all  that  is  necessary  is  to  carefully  filter  the  solution  and  evapo- 
rate, to  obtain  a  product  that  will  redissolve  in  distilled  water  with- 
out showing  any  signs  of  floating  particles.  When  you  come,  how- 
ever, to  critically  examining  such  solutions,  you  will  discover  that 
the  first  thing  is  to  get  distilled  water  which  under  the  most  rigid 
tests  will  show  no  tiny  particles  floating  in  it.  So  far  I  have  never 
seen  any  of  the  above  mentioned  substances  or  distilled  water  that 
would  show  absolutely  no  signs  of  tiny  floating  particles  when 
viewed  by  the  naked  eye  against  a  dark  background  under  an  electric 
light.  Remember,  though,  that  one  liter  or  even  five  liters  of  such 
a  solution  will  leave  no  weighable  residue  on  a  filter  paper;  in  fact, 
unless  the  filter  is  hard  and  smooth  it  is  very  likely  to  make  the 
solution  worse. 
After  problems  connected  with  the  manufacture  are  solved,  there 
come  up  also  numerous  questions  in  regard  to  containers  used.  For 
example,  glass  that  contains  any  trace  of  alkali  soluble  in  water  (and 
this  is  the  rule  rather  than  the  exception)  cannot  be  used  in  making 
ampoules  containing  very  delicate  substances,  for  strychnine  alkaloid 
will  be  precipitated  from  its  salts  and  a  delicate  organic  preparation 
like  adrenalin  will  be  quite  rapidly  destroyed.  Containers  made  from 
coke  tin  plate  cannot  be  used  to  hold  materials  that  might  slowly 
attack  iron,  whereas  charcoal  tin  plate  is  satisfactory,  the  difference 
being  that  the  former  has  occasional  exceedingly  minute  holes 
through  the  tin,  while  in  the  latter  the  tin  coating  is  uniform  and 
unbroken. 
When  we  come  to  the  consideration  of  the  more  difficult  prob- 
lems connected  with  medicinal  substances  and  their  development  we 
reach  a  vast  unknown  region  that  has  been  but  most  imperfectly  ex- 
plored. We  speak  glibly  oftentimes  of  relationship  between  chem- 
ical constitution  and  physiological  action,  but  our  actual  and  definite 
knowledge  of  the  relationship  is  at  the  best  extremely  limited.  We 
have  acquired  what  seems  like  a  considerable  amount  of  empirical 
understanding  that  certain  effects  are  in  some  way  associated  with 
certain  combinations  of  elements  or  radicals,  but  we  may  draw  a 
hasty  conclusion  merely  to  find  that  there  are  numerous  exceptions 
