4APJrT'i8P7H4ARM}  Loss  of  Weight  in  Drying  Air-dry  Drugs.  173 
That  examination  is  inadequate  as  a  guide  for  the  year,  as  some 
months  are  wet  and  others  more  dry,  necessarily  causing  the  drug  to 
vary  in  the  amount  of  moisture  it  contains. 
Prof.  Maisch  suggested  to  me  the  importance  of  making  a  series  of 
experiments  with  a  number  of  drugs  in  each  month  during  the  year, 
for  the  purpose  of  ascertaining  how  much  they  would  vary  during  wet 
and  dry  weather,*  and  thus  to  determine  the  importance  of  using 
only  drugs  that  are  thoroughly  dried  in  the  manufacture  of  the  many 
galenical  preparations,  and  especially  tinctures,  syrups  and  fluid  ex- 
tracts and  the  like,  which  must  vary  in  strengtn  as  made  from  anhy- 
drous or  merely  air-dry  drugs.  I  give  below  the  results  of  my  expe- 
riments, commencing  with  January,  and  continuing  during  the  year 
till  December,  1873. 
The  operation  was  conducted  in  the  following  manner :  The  drug 
was  weighed  from  the  stock  on  hand  about  the  first  of  each  month, 
and  then  exposed  to  a  heat  of  about  110°  Fahrenheit  in  a  common 
cooking  stove  oven  until  it  ceased  losing  weight.  The  loss  was  noted, 
and  the  material  was  then  exposed  to  the  atmosphere  until  the  end  of] 
the  month,  when  it  was  re-weighed  in  order  to  find  out  how  much| 
moisture  had  been  re-absorbed  during  the  month.  It  will  be  found 
upon  examination  that  the  quantity  of  moisture  lost  and  re-absorbed[ 
varies  considerably,  owing  to  the  condition  of*  the  weather  at  the  time 
when  the  drug  was  weighed;  for  instance,  supposing  at  the  first  of  thel 
month  the  article  was  weighed  in  dry  weather,  the  loss  in  moisturq 
was  invariably  smaller  than  if  it  were  weighed  in  rainy  weather;  thenj 
again  at  the  end  of  the  month,  when  the  drug  was  re-weighed  in  wet} 
weather,  the  amount  of  moisture  re-absorbed  was  always  larger. 
The  figures  presented  by  the  writer  are  as  correct  as  they  possibly! 
can  be,  care  having  been  taken  to  avoid  the  loss  of  material  on  th 
*Our  suggestion  was  not,  to  exsiccate  the  drugs  every  month  for  the  pur 
pose  of  ascertaining  the  percentage  of  moisture  contained  in  them,  but  to  makd 
that  determination  once  only,  at  the  beginning  of  the  year,  and  to  reserve  an 
other  portion  of  the  same  drag  for  the  purpose  of  weighing  it  once  or  twice 
month,  in  order  to  determine  the  variation  of  the  actual  weight  of  the  drug 
kept  in  the  usual  manner  throughout  the  year.  It  is  obvious  that  the  relativ 
strength  of  the  galenical  preparations  of  air-dry  drugs  would  be  the  same,  if  th 
actual  weight  of  these  drugs  did  not  differ  throughout  the  year,  in  wet  or  dr 
weather,  &c. ;  while  in  actual  medicinal  strength  they  are  undoubtedly  weake 
than  if  they  had  been  made  from  anhydrous  drugs. — Editor  Amer.  Journ.  Pe 
