422    DETERMINATION  OP  TALLOW  OR  STEARIC  ACID  IN  WAX. 
that  the  melting  points  found  by  Legrip  do  not  quite  agree  with 
those  given  by  Lepage. 
M.  Legrip  is,  therefore,  of  opinion,  that  a  more  correct  cereo- 
meter  could  be  obtained  by  comparing  the  specific  weights  of 
wax  and  tallow.  He  found  the  specific  weight  of  the  white  and 
yellow  wax  to  be  =0.962,  and  that  of  tallow  —  0.881.  If,  how- 
ever, these  data  be  compared  with  those  given  by  other  experi- 
menters, we  find  also  here  considerable  discrepancies  ;  for,  ac- 
cording to  Muschenbrock  and  Brisson,  the  specific  weight  of 
the  yellow  wax  is  0.960 — 0.964,  and  that  of  white  wax,  0.966 — 
0.968.  The  specific  weight  of  sheep  tallow  Mushenbrock  found 
to  be  =  0.943,  and  Brisson,  =0.923-  That  of  bullocks'  tallow 
is  after  M.  —0.955,  and  after  B.  =  0.923,  consequently  much 
greater  than  Legrip  has  found  it. 
The  principles  of  Legrip's  cereometer  is,  however,  notwith- 
standing these  differences,  correct  and  worthy  of  notice ;  it  is 
this — alcohol,  of  a  given  specific  weight,  is  diluted  with  so  much 
water,  that  the  wax  placed  in  it  at  a  temperature  of  15°  C. 
neither  sinks  nor  swims  on  the  surface  of  the  fluid,  but  keeps  in 
the  middle  of  the  same ;  it  is,  then,  only  necessary  to  employ 
the  areometer,  in  order  to  determine  from  the  specific  weight  of 
the  alcohol,  the  purity  or  the  degree  of  adulteration  of  the  wax. 
Assuming  the  specific  weight  of  the  wax  to  be  =0.962,  its  purity 
is  established,  if  it  keeps  in  the  midst  of  alcohol  of  this  specific 
weight,  or  of  29°  by  Gay  Lussac's  areometer,  whilst  a  specific 
weight  of  0.881  or  46°  after  Gay  Lussac,  indicates  the  pure 
tallow.  A  mixture  of  these  two  standard  fluids,  taken  at  equal 
parts,  represents  a  mixture  of  equal  proportions  of  weight  of 
wax  and  tallow,  and  corresponds  with  37°. 5  on  Gay  Lussac's 
areometer  : 
33°. 3  G.  L.  areometer  =75  wax  and  25  tallow. 
37°.5  «  «        =50   "     «    50  « 
41°.7  "  «        =25   "     •<   75  « 
46°. 0  "  «        —  0   "     «  100  « 
The  Druggist. 
