Am.  Jour.  Pharm.  ) 
Aug.  1, 1873.  S 
On  Butter. 
361 
H802).  capronic  acid  (C6H12Q2),  caprylic  acid  (C8H1602),  and  caprinic 
acid  (C10H20O2).  (Wagner  and  Oookes.)  The  last  four  glycerides 
are  the  characteristic  fats  of  butter. 
When  butter  has  been  decomposed,  the  rancid  taste  and  smell  make 
its  condition  evident  to  every  one.  The  skill  of  the  analyst  is  most 
frequently  directed  to  the  detection  of  fats  from  the  flesh  of  animals 
or  from  the  vegetable  kingdom.  The  fats  which  are  generally  used 
as  adulterants  or  as  substitutes  for  butter  are  suet,  tallow,  dripping, 
lard,  a  mixture  of  refined  fats  sold  under  various  names,  palm  and 
similar  vegetable  oils.  The  most  characteristic  ingredients  in  these 
fats  are  stearin,  margarin  and  palmitin. 
Stearin  is  a  crystalline  fat,  melting  at  144°  F.,  and  solidifying  at 
124°  F.,  soluble  in  hot  ether,  or  in  seven  times  its  weight  of  boiling 
alcohol,  but  deposited  from  both  these  solutions  on  cooling. 
Margarin  forms  scales,  which  melt  at  about  116°  F.,  and  are  solu- 
ble in  warm  ether. 
Palmitin  is  a  solid  crystalline  fat,  melting  at  from  118°  to  143°, 
and  solidifying  at  114°.  It  is  readily  soluble  in  ether,  sparingly 
soluble  in  alcohol.  Stearin,  margarin,  and  palmitin  are  seldom  ob- 
tained pure;  they  occur  in  Nature  dissolved  in  olein  and  other  oils, 
which  lower  the  melting-point.  For  instance,  mutton  and  beef  suet* 
lard  and  palm  oil  melt  at  temperatures  from  25°  to  55°  below  the 
melting-points  of  stearin  and  palmitin. 
In  drawing  up  the  following  table  for  the  examination  of  butter,  I 
have  made  free  use  of  the  observations  of  Dr.  Ballard  [Chemical  Netvs, 
vols,  iv  and  v),  and  the  scheme  of  Dr.  Parkes  ("Hygiene^  chap,  v, 
section  xi) ;  but  I  depend  chiefly  on  my  own  observations  on  a  large 
number  of  samples  from  different  sources,  made  during  the  years 
1871  and  1872. 
Table  for  the  Examination  of  Butter. 
1.  Weigh  out  an  ounce  of  the  sample  of  butter  which  is  to  be  ex- 
amined, place  it  in  a  test-tube  seven-eighths  of  an  inch  in  diameter, 
and  melt  by  placing  the  tube  in  hot  water.  Place  a  thermometer, 
with  a  pear-shaped  bulb,  so  that  the  bulb  shall  be  in  the  middle  of  the 
fat  about  one  inch  below  the  surface,  and  allow  the  whole  to  cool 
spontaneously.  If  the  quantity  of  water  in  the  butter  be  large,  it 
will  collect  in  the  tube  below  the  fat ;  the  casein  will  also  collect  in 
the  lower  part  of  the  tube.  Watch  the  mass  as  it  cools,  and  note 
when  solidification  commences  and  when  it  is  complete.  The  follow- 
ing are  the  average  solidification-points  : — 
