362 
On  Butter. 
J  Am.  Jotjr.  Pharm. 
\    Aug.  1, 1873. 
With  pure  butter  the  thermometer  is  obscured  between  74°  and  68°, 
and  the  mass  is  solid  at  60°. 
Beef  dripping  obscures  the  thermometer  at  79°,  and  is  solid  at  72°. 
Mutton  dripping  obscures  the  thermometer  at  about  85°,  and  is 
solid  at  84°. 
Lard  obscures  the  thermometer  at  84°,  and  is  solid  at  from  79°  to 
70°,  but  it  often  remains  as  soft  as  butter  at  a  much*  lower  tempera- 
ture. # 
Mixtures  solidify  at  intermediate  temperatures. 
2.  Determine  the  quality  of  the  butter  by  the  taste  and  smell  of 
the  re-congealed  fat  and  of  the  original  sample. 
3.  Examine  several  portions  of  the  original  sample  by  means  of  a 
good  microscope,  using  a  one-quarter  inch  or  one-fifth  inch  object 
glass.  In  butter  made  from  milk  or  cream,  nothing  is  seen  except 
the  characteristic  globules,  and  the  granular  masses  of  curd,  and  the 
cubical  crystals  of  salt.  The  hard  fats  of  butter  are  present  in  the 
globules  in  a  state  of  solution,  and  are  not  recognizable  in  a  separate 
form. 
If  stearic  acid,  stearin  or  palmitin  be  present  in  separate  form, 
they  will  be  recognized  by  single  fusiform  crystals,  or  star-like  ag- 
gregations of  acicular  crystals.  They  indicate  the  presence  of  melted 
fats. 
Other  substances,  such  as  starch,  flour,  palm  oil  corpuscles,  Irish 
moss,  coloring  matter,  etc.,  may  also  be  distinguished  by  the  micro- 
scope, as  distinct  from  butter  or  fats. 
4.  Examine  the  same  portions  with  the  same  object-glass,  together 
with  a  polariscope,  consisting  of  two  Nicol's  prisms  and  a  selenite 
plate.  The  crystals  referred  to  in  (3)  polarized  light,  and  when  viewed 
by  the  polariscope  are  more  distinctly  defined.  Particles  of  suet  and 
other  fats,  which  have  not  been  melted,  may  also  be  distinguished  by 
their  action  on  polarized  light,  by  their  amorphous  form,  and  by  their 
membranes. 
5.  Repeat  the  microscopic  examination  after  the  addition  of  tinc- 
ture of  iodine,  acetic  acid,  and  other  reagents  usually  employed  to  de- 
tect substances  other  than  fat. 
6.  Weigh  carefully  a  convenient  quantity  of  the  sample,*say  1  oz., 
in  a  tared  porcelain  dish,  evaporate  in  a  water-bath,  or  in  air-bath, 
at  212°,  until  free  from  water,  and  weigh  again  ;  the  difference  is  the 
amount  of  water  per  ounce,  which  should  not  exceed  35  grs.  (5  to  10 
per  cent.  Parkes). 
