496 
Preservation  of  Food. 
{Am.  Jour.  Phiem. 
Nov.  1,  1873. 
Second. — Immersing  the  vessels  which  have  been  thus  charged — and  well 
closed — completely  in  cold  water,  gradually  heating  to  boiling,  and  continuing 
the  boiling  for  a  certain  time.  Vegetable  substances  to  be  put  into  the  vessels 
in  a  raw  and  crude  state,  and  animal  substances  to  be  partly  or  half  cooked, 
although  these  may  be  put  in  raw. 
Lastly. — Although  the  application  of  the  water-bath  as  described  is  prefer- 
red, an  oven  or  a  stove  or  a  steam-bath  may  be  used,  and  also  the  aperture,  or 
a  small  portion  thereof,  may  be  left  open,  and  is  closed  when  the  effect  of  heat 
has  taken  place. 
This,  is  the  whole  art  of  canning  fruits  as  practiced  to-day,  although 
experience  has  suggested  certain  modifications.  Numerous  patents 
have  since  been  granted,  both  in  England  and  in  this  country,  for 
details  of  the  process,  such  as  using  a  bath  of  chloride  of  calcium 
in  place  of  pure  water,  as  by  this  means  a  much  higher  temperature 
can  be  obtained.  Another  patent  is  a  modification  of  the  last  clause 
of  the  above ;  the  cans  are  first  closed  completely  and  then  a  small 
hole  is  punched  in  t  he  cover  to  allow  the  heated  air  and  steam  to 
escape ;  this  is  afterwards  closed  by  soldering.  Various  modifications 
of  the  vessels  above  described,  such  as  peculiar  methods  of  construct- 
ing the  mouths,  using  rubber  in  place  of  leather,  and  using  clamps  in 
place  of  the  screw  cap,  are  also  found  on  the  records ;  but  in  all  essen- 
tial particulars  the  old  patent  remains  unchanged. 
A  great  deal  of  interest  has  been  recently  excited  by  a  decision  of 
Judge  Clifford,  of  the  U.  S.  Court,  in  the  case  of  a  patent  granted  to 
Isaac  Winslow  for  preserving  green  corn.  In  the  course  of  this  trial 
the  processes  now  used  were  pretty  fully  explained,  as  follows  :  The 
corn,  or  other  vegetable,  is  gathered  in  as  fresh  a  state  as  possible, 
and  is  prepared  by  removing  all  refuse  or  imperfect  parts,  and  such 
parts  as  would  add  to  the  bulk  of  the  finished  product,  without  in- 
creasing its  value,  as  the  hulls  of  peas  and  beans  and  the  cores  of  the 
corn.  The  prepared  articles  are  placed  upon  coolers,  which  are  sur- 
rounded by  ice  water  until  wanted  for  use.  The  utmost  car©  must 
be  used  in  this  preliminary  process  to  avoid  any  mixture  of  immature, 
over-ripe  or  defective  specimens,  as  a  few  such  will  spoil  the  lot.  The 
cans  are  filled  with  the  vegetables  as  quickly  as  possible  and  are  her- 
metically sealed  by  soldering  on  the  covers.  Tin  is  almost  exclu- 
sively used  for  packing,  at  present,  as  great  loss  is  incurred  from 
breakage  when  glass  is  employed.  The  tins  are,  moreover,  much 
easier  to  make  and  keep  tight  than  is  the  case  with  glass  jars.  The 
cans  are  then  placed  in  the  bath,  and  heated  from  one-half  of  an  hour 
