434 
TINFOIL  AS  A  PRESERVATIVE,  ETC. 
digest  for  half  an  hour,  constantly  stirring,  then  add  the  savin- 
tops,  and  further  digest  for  twenty  minutes ;  lastly,  strain 
with  pressure  through  calico  or  flannel,  stirring  occasionally 
until  cold. 
Resulting  ointment,  pale  yellowish-green,  mth  the  odor  of 
savin  distinctly  marked,  which  odor  I  have  failed  to  detect 
in  most,  if  not  all  bought  specimens.  The  addition  of 
gum  benzoin  (judging  from  its  preservative  effect  on  other  oint- 
ments) will,  in  this  case,  I  hope,  tend  to  prevent  any  decided 
change  from  taking  place. — Pharm.  Journ.^  July  2,  1870. 
Manhey  Grove,  Stratford^  June  2d,  1870. 
ON  THE  USE  OF  TINFOIL  FOR  PRESERVINO  SUBSTANCES 
LIABLE  TO  CHi^NGE  ON  EXPOSURE  TO  AIR. 
By  Ernest  Baudrimont. 
Tin  reduced  to  thin  sheets  has  for  many  years  been  employed 
for  preserving  a  great  number  of  substances  from  the  action  of 
air  and  moisture.  The  thin  leaves  (foil)  of  this  metal  are 
essentially  repellent  of  moisture.  When  cemented  to  the  sur- 
face of  damp  walls,  they  protect  the  paperhangings  which  may 
be  afterwards  applied,  and  they  are  in  like  manner  used  for 
lining  the  interior  of  boxes  and  drawers  in  which  dried  medicinal 
leaves  and  flowers  are  kept.  It  has  long  been  the  practice  to- 
enclose  chocolate  in  tinfoil,  to  prevent  the  fatty  matter  contained 
in  it  from  soiling  the  paper  which  forms  the  outside  wrapper ;  in 
the  same  way  butter  of  cacao  itself  is  preserved,  and  some  sorts 
of  sweetmeats,  sausages,  and  cheese  are  among  the  articles 
similarly  protected.  Tobacco-pouches  are  lined  with  tinfoil  to 
preserve  the  flavor  and  humidity  of  the  tobacco.  Cakes  of  opium 
are  kept  in  a  moist  and  uniform  state  by  wrapping  them  in  this 
material,  and  bisulphate  of  soda  is  kept  in  the  same  way,  for  use 
in  making  artificial  Seltzer  water  with  Briet's  apparatus.  Lastly, 
on  account  of  the  opacity  of  tinfoil  to  the  rays  of  light,  bottles 
are  coated  with  it  for  the  purpose  of  excluding  light  from  vege- 
table substances  which  would  be  injured  by  its  action. 
Notwithstanding  the  knowledge  of  all  these  facts,  it  might  be 
said  that  the  application  of  tinfoil  for  the  preservation  of  sub- 
