^vemberSi10'}    Re  cent'  Literature  Relating  to  Pharmacy.  565 
comparison  of  the  freezing  point  of  a  solution  with  that  of  its  sol- 
vent alone,  is  traced  in  historical  order. 
Raoult's  law  (depression  of  freezing  point  is  directly  proportioned 
to  amount  of  solids  dissolved) ;  the  discovery  that  equi-molecular 
solutions  have  the  same  depression  of  freezing  point ;  the  value  of 
this  fact  in  estimating  molecular  weights  are  all  noted  in  the  paper, 
but  omitted  here,  as  details  can  be  found  in  any  text-book  on  physi- 
cal chemistry.  In  the  paper  particular  stress  is  laid  on  the  fact  that 
depression  of  freezing  point  of  a  solution  is  in  direct  proportion  to 
the  osmotic  pressure  of  same,  hence  by  reading  freezing  point  de- 
pression of  a  liquid,  we  learn  its  osmotic  pressure.  This  measure- 
ment of  osmotic  pressure  is  of  great  value  in  physiological  chemistry, 
and  the  estimation  of  depression  of  freezing  point  introduced  by 
Dreser  in  1891  has  now  become  an  essential  part  of  the  clinical  ex- 
amination of  the  liquids  of  the  organism,  such  as  blood,  serum, 
urine,  lymph,  milk  saliva,  sweat,  etc.  It  is  interesting  to  note  that 
all  the  physiological  liquids  save  urine,  have  about  the  same  freez- 
ing point  depression  (hence  same  osmotic  pressure)  as  blood  serum; 
that  is,  in  the  normal  state  of  the  organism,  all  its  natural  liquids 
are  in  physical  equilibrium. 
Cryoscopy  is  of  interest  to  pharmacists  inasmuch  as  the  measure- 
ment of  freezing  point  is  becoming  a  necessary  part  of  urine  exam- 
ination. H.  V.  A. 
SPURIOUS  SANDARAC. 
R.  Haneke  (Pharm.  Jy,  1900,  p.  79),  reports  on  a  fictitious  sandarac 
of  Spanish  origin.  Physically  it  was  an  exceedingly  fine  specimen, 
consisting  of  elongated  and  rounded  tears,  pale  lemon-yellow  in 
color.  On  chewing,  it  adhered  to  the  teeth,  and  melted  at  the 
temperature  of  the  water  bath,  while  sandarac  is  not  materially 
changed  at  1 300  C.  (Some  varieties  of  colophony  possess  as  high 
a  melting  point  as  1 35 0  C,  L.  F.  K.).  Sandarac  has  an  acid  num- 
ber varying  from  1 36-140.  (The  acid  number  of  colophony  varies 
from  130  to  181,  L.  F.  K.).  The  above  sample's  acid  number  was 
169.  From  the  above  date  and  etc.,  behavior  towards  solvents 
there  is  little  doubt  but  that  the  specimen  consisted  of  colophony. 
L.  F.  Kebler. 
FOOD  VALUE  OF  EXTRACT  OF  MEAT. 
L.  Furst,  (Chem.  Ztg.y  24,  994,)  reviews  the  statement  made  by 
a  number  of  authorities  relative  to  the  true  nutritive  constituents 
