VARIETIES. 
185 
thorities.  The  product  of  the  last  three  years  has  been  about  180,000 
pounds  annually,  worth  at  the  place  of  exportation  eight  dollars  a  pound,  or 
$1,440,000  each  year.  In  a  pound  of  small  leeches  there  are  from  two 
hundred  and  fifty  to  four  hundred  leeches.  A  pound  of  large  leeches  contains 
half  that  proportion.  There  are  probably  from  50,000,000  to  G0,000,000 
of  leeches  annually  exported  from  Turkey.  They  are  sent  chiefly  to  Trieste, 
Marseilles,  and  London,  and  some  to  America  direct.  The  price  varies 
greatly  at  these  ports,  accoiding  to  the  supply.  The  prices  current  of  Mar- 
seilles as  regularly  include  the  price  of  leeches,  as  of  wheat  and  wool." — 
Boston  Med.  and  Sur.  Jour.,  Aug.  4th,  1852. 
On  Elastic  Collodion.  By  M.  E.  Lauras. — Having  made  collodion  the 
subject  of  a  special  study,  and  the  object  which  I  sought  having  been  at- 
tained, I  now  communicate  the  good  results  I  have  obtained  by  the  modus 
faciendi  which  I  employ. 
The  important  improvement  to  be  made  in  this  compound,  which  hitherto 
has  not  been  of  very  frequent  application  in  therapeutics,  consists  in  giv- 
ing efficacy  to  it  and  in  preventing  the  sufferings  produced  by  its  application 
on  any  portion  of  the  body,  and  principally  on  the  articulations,  which  are 
much  constricted  after  having  been  covered  with  it,  an  effect  due  to  its  want 
of  suppleness  and  elasticity,  and  which  the  skin  requires  both  for  stretching 
and  contracting. 
By  adopting  the  following  formula,  every  inconvenience  is  obviated,  col- 
lodion becomes  easy  of  employment,  and  enables  the  patient  to  move  without 
suffering  pain: — 
Sulphuric  acid  of  sp.  gr.  1.847,  300  grms.  ;  nitrate  of  potassa  (very  dry) 
200  grms.  Mix  together  in  a  stone-ware  or  porcelain  pot5  and  add  carded 
cotton,  ten  grms. 
Leave  in  contact  for  twelve  minutes ;  withdraw  the  cotton,  wash  it  with 
cold  water  to  remove  the  acid  which  it  retains,  and  after  two  or  three  rins- 
ings, immerse  it  in  water  containing  thirty  grms.  of  subcarbonate  of  potassa 
in  solution  in  1000  grms.  of  water;  plunge  it  again  into  ordinary  water, 
agitate  well,  and  dry  at  a  temperature  of  77°  to  86°  F. 
The  cotton,  thus  prepared,  takes  the  name  of  Xyloidine,  and  may  after- 
wards be  mixed  with  the  ether  and  the  other  substances  which  form  it  into 
elastic  collodion. 
Elastic  collodion.  Xyloidine  8  grms.;  ordinary  sulphuric  ether  125 
grms.  Place  in  a  wide-mouthed  flask,  and  add  alcohol  of  sp.  gr.  .825,  8 
grms.  Agitate  and  then  make  a  mixture  composed  of  Venice  turpentine  2 
grms.;  castor  oil  2  grms.  ;  white  wax  2  grms. ;  sulphuric  ether  6 grms.  Heat 
together  the  first  three  substances,  add  the  ether,  and  combine  the  two  mix- 
tures.— Repertoire  de  Phar made  and  the  Chemist,  from  London  Pharm.  Jour., 
Dec.  1st,  1852. 
On  the  Preservation  of  Fruits  and  their  Juices,  by  the  application  of  Steam. 
By  Mayet.    The  author  has  previously  proved  by  a  research,  that  the  heat 
