23  A     NEW  FLUID  FOR  PRESERVING  NAT.  HIST.  SPECIMENS. 
spirits  and  then  transfer  successively  to  stronger,  and  for  some 
objects,  as  Medusae,  no  other  treatment  will  succeed. 
Solution  B.  I. 
Soft  water,  1  gallon. 
Solution  A.  I,       .       .       .       .       1  qt. 
Arseniate  of  potassa,     .       .       .       1  oz. 
Another  solution  with  double  the  amount  of  water  may  be  made 
if  desired,  and  called  solution  B.  II. 
To  preserve  animals  with  these  solutions  they  are,  if  insects  or 
marine  invertebrates,  ordinarily  placed  first  in  solution  B.  I,  but 
if  the  weather  be  cool  it  would  be  better  in  many  cases  to  employ 
first  B.  II,  and  in  the  case  of  all  marine  animals  washing  first  in 
fresh  water  is  desirable,  though  not  essential.  If  the  specimens 
rise  to  the  surface  they  should  be  kept  under  by  mechanical 
means.  After  remaining  for  several  hours,  or  a  day,  varying 
according  to  its  size  and  the  weather,  in  the  B.  I.  solution  it  may 
be  transferred  to  A.  Ill,  and  then  successively  to  A.  II,  and  A. 
I,  and  when  thus  fully  preserved  it  may  be  transferred  to  a  fresh 
portion  of  the  last  solution,  which  has  been  filtered  clear  and 
bright,  and  put  up  in  a  cabinet,  when  no  further  change  will  be 
necessary  if  the  bottle  or  other  vessel  be  properly  secured  to 
prevent  the  escape  of  the  fluid  by  crystallization  around  the 
opening.  To  prevent  this  the  stopper,  whether  of  cork  or  glass, 
together  with  the  neck  of  the  bottle  or  jar,  may  be  covered  with 
a  solution  of  parafline  or  wax  in  turpentine  or  benzole,  which 
should  be  applied  only  when  the  surfaces  are  quite  dry  and 
clean.  The  length  of  time  that  any  specimen  should  remain  in 
each  of  the  solutions  is  usually  indicated  by  their  sinking  to  the 
bottom  when  saturated  by  it.  In  general  the  more  gradually 
this  saturation  with  the  saline  matter  takes  place  the  less  the 
tissues  contract  or  change  in  appearance.  In  many  cases,  how- 
ever, fewer  changes  than  indicated  above  will  be  effectual.  I 
have  in  some  cases  succeeded  well  with  but  two  solutions  below 
A.  I.  For  vertebrates,  except  fishes,  the  solution  A.  II.  will 
usually  be  found  strong  enough  for  permanent  preservation,  es- 
pecially when  the  object  is  small  or  dissected.  If  the  entire 
animal  be  preserved,  when  larger  than  two  pounds  in  weight,  it 
should  be  injected  with  the  fluids,  especially  B.  I.  and  the  final 
