480  Deterioration  of  Artificial  Foods.  {^m6ix^^\m' 
tion  of  the  albuminous  matter,  after  which  the  liberation  of  vola- 
tile fatty  acids  and  sulphuretted  gases  takes  place  and  the  produc- 
tion of  the  toxic  principles  or  ptomaines  is  the  last  step  in  the 
series  of  changes  which  take  place. 
It  therefore  follows  that,  if  air  and  moisture  be  excluded,  food 
products  will  keep  for  an  indefinite  period  and  this  has  been  borne 
out  by  experimental  work  performed  by  numerous  investigators  on 
the  subject. 
When  the  package  is  not  air  tight  the  product  should  always  be 
kept  in  a  cool  dry  place,  as  this  is  the  safest  way  to  minimize  the 
chances  of  deterioration  occurring. 
Another  change  which  often  takes  place  in  products  of  this  kind 
is  one  which  involves  purely  physical  processes  and  which  is 
applicable  also  to  many  other  substances  kept  in  the  store,  such  as 
ground  drugs  and  spices. 
This  change  is  produced  by  the  absorption  of  odorous  conv 
pounds  and  subsequent  alteration  of  odor  and  flavor,  either  by  the 
close  proximity  of  some  volatile  body  having  a  powerful  odor,  or 
by  the  standing  in  an  atmosphere  surcharged  with  such  odorous 
compounds.  It  is  a  well  known  fact  that  most  drug  stores  have  a 
distinctive  odor,  usually  of  an  unpleasant  character,  and  at  certain 
seasons  of  the  year,  when  naphthalene,  or  "coal  tar  camphor"  as 
it  is  termed,  is  in  great  demand,  some  druggists  have  window  dis- 
plays in  which  a  large  amount  of  the  product  is  heaped  up  so  as  to 
attract  attention.  As  this  compound  is  very  volatile  and  of  a  pecu- 
liar penetrating  odor  it  can  easily  be  seen  that  when  the  store  is 
closed  up  for  the  night  so  that  there  is  no  ventilation  to  carry  the 
odor  out,  every  container  in  the  store  which  is  not  practically  air- 
tight will  be  subjected  to  the  influence  of  this  vapor,  and  in  such 
cases  as  the  food  products,  ground  spices  and  many  of  the  ground 
drugs,  enough  of  the  odor  is  often  absorbed  to  be  readily  appreci- 
able to  the  senses  for  a  long  time  afterward.  A  retail  druggist 
some  time  ago  was  questioned  on  this  subject  and  in  reply  said  that 
he  had  learned  this  fact  after  losing  two  customers  who  had  bought 
ground  spices  from  him  after  he  had  been  having  a  window  display 
of  flake  naphthalene,  and  that  he  now  handled  the  substance  only  in 
sealed  cartons,  and  had  also  taken  the  trouble  to  rearrange  his 
drawer  stock  so  that  the  strongly  odorous  substances  like  asafcetida, 
camphor,  etc.,  were  kept  away  from  such  substances  as  ground  elm 
bark,  ground  spices,  etc. 
