Am'M°ay?i?93arm'}    Preparation  of  Compressed  Tablets,  215 
ammonia  Si ;  dampen  with  alcohol  and  water,  run  through  a  No.  XX 
sieve  and  dry.  Make  into  5-grain  tablets,  and  sell  them  to  your 
customers  as  the  best  in  the  market ;  for  they  are  of  your  own  make. 
These  will  be  what  they  profess  to  be,  and  your  patrons  will  soon 
find  it  out. 
If  you  understand  the  principles  of  pharmacy,  you  can  soon  learn 
how  to  make  compressed  tablets,  and  learning  how,  you  will  become 
better  druggists.  Of  course,  as  graduates  you  know  the  chemical 
relation  of  drugs,  how  and  when  chemical  reactions  take  place  ;  this 
will  serve  a  good  purpose  here.  For  some  time  past  there  have 
been  used  many  tablets  of  calomel  and  bicarbonate  of  soda.  Your 
chemistry  will  tell  you  if  these  salts  be  mixed  wet,  and  granulated, 
decomposition  will  take  place,  and  the  question  would  be,  how  to 
avoid  it?  You  might  do  so  in  several  ways;  but  I  will  mention 
only  one.  Take  bicarbonate  of  soda  3xss,  gum  arabic  3ss,  mix  and 
dampen  with  water,  run  through  a  No.  40  sieve,  dry  and  put  into  a 
bottle,  add  calomel  ,3iss,  and  shake  this  until  every  granule  is  coated. 
The  calomel  will  adhere  to  the  small  particles  of  soda  hardened  with 
the  gum  ;  this  will  obviate  any  necessity  of  talc.  The  object  is  to 
prevent  the  soda  and  calomel  coming  together  in  a  damp  condition. 
Make  up  into  one-grain  tablets,  each  of  which  will  contain  ^  of  a 
grain  of  calomel  This  illustrates  pretty  well  how  chemical  incom- 
patibles  may  be  put  together  in  a  compressed  form  and  still  retain 
their  individuality,  and  still  better  how,  in  some  cases,  a  dangerous 
result  may  be  avoided  from  mixing  together  articles  innocent  in 
themselves,  but  deleterious  as  factors  in  a  product.  The  soda  hard- 
ened with  the  gum  is  scarcely,  in  the  least,  hygroscopic  and  the 
tablets  made  with  it,  in  the  manner  stated,  will  keep  without  change 
fully  as  long  as  a  druggist  who  has  them  for  sale  desires.  The 
calomel,  being  put  in  last,  answers  the  purpose  of  its  indications  as 
a  medicine,  and,  at  the  same  time  as  a  protection  against  adhesion 
to  the  dies  and  punches.  In  all  these  combinations  a  certain  amount 
of  brains  is  a  sine  qua  non,  and  may  be  written  on  the  formula  quan- 
tum sufficit.  Here,  as  elsewhere,  the  dictum  of  the  teacher  cannot 
give  individual  skill,  nor  can  the  dreams  of  theory  take  the  place  of 
applied  knowledge. 
At  the  start  remember,  and  never  let  it  be  forgotten,  that  facts 
established  cannot  be  changed,  and  it  is  with  facts  you  have  to 
deal.    The  metal  of  which  the  dies  and  punches  are  made  is  a  fixed, 
