Am.  Jour.  Pharm.  ) 
Aug.  1,  1873.  J 
On  Butter. 
363 
7.  Dissolve  the  residue  in  ether,  warming  gently  until  the  whole 
of  the  fat  is  dissolved,  filter  through  a  weighed  filter-paper,  collecting 
the  filtrate  in  a  beaker,  then  wash  the  dish  and  filter-paper  with  ether 
until  a  total  of  5  or  6  oz.  has  been  used,  and  allow  the  whole  to  stand 
for  some  time  at  a  temperature  of  65°. 
8.  Dry  the  precipitate  on  the  filter-paper,  and  weigh ;  deduct  the 
weight  of  filter-paper  ;  the  remainder  is  approximately  the  amount 
of  curd,  or  casein,  and  salt. 
9.  Wash  the  precipitate  with  boiling  water,  dry  at  212°,  and 
weigh ;  deduct  the  weight  of  filter-paper ;  the  remainder  is  the 
amount  of  curd  or  casein,  which,  in  good  butter,  should  not  exceed 
15  grs.  per  oz.  (3  to  5  per  cent.;  Parkes). 
10.  Estimate  the  salt,  by  means  of  nitrate  of  silver,  in  the  aqueous 
washings  from  (9),  or  wash  another  weighed  portion  of  butter  thor- 
oughly with  distilled  water,  and  determine  the  salt  by  nitrate  of  sil- 
ver. It  should  not  amount  to  more  than  8  grs.  per  oe.  in  fresh  but- 
ter (0.5  to  2  per  cent.  ;  Parkes),  or  35  grs.  per  oz.  in  salt  butter  (8 
per  cent.  ;  Parkes.) 
11.  If  the  ethereal  solution  of  the  fat  from  (7)  has  formed  a  deposit 
at  65°,  decant  and  filter  off  the  clear  solution,  and  examine  the  de- 
posit, which  is  probably  stearin,  according  to  (12). 
Evaporate  the  ethereal  solution  down  to  4  oz.,  and  allow  it  to  stand 
for  several  hours  at  65°.  Filter  off  the  deposit,  which  probably  still 
contains  stearin,  and  examine  it  also  according  to  (12). 
Allow  the  ethereal  solution  to  evaporate  down  to  3  oz.,  and  allow 
it  to  stand  for  some  time  at  65°.  Filter  off  the  deposit,  which  may 
still  contain  some  stearin  mixed  with  palmitin,  and  examine  it  sepa- 
rately according  to  (12).  If  the  butter  is  adulterated,  some  of  the 
stearin,  and  much  of  the  palmitin,  will  still  remain  in  solution,  and 
may  be  obtained  by  continuing  the  process  of  spontaneous  evapora- 
tion. 
Some  samples  of  pure  butter  yield  no  deposit  from  3  oz.  of  ether  at 
65°  ;  but  fairly  good  butter  will  generally  form  a  slight  deposit,  the 
amount  of  which  varies  in  different  samples.  A  sample  of  butter 
known  to  be  pure  should  be  examined  side  by  side  with  the  sample 
suspected  to  be  adulterated  ;  and,  as  winter  butter  is  a  more  solid  fat 
than  summer  butter,  the  former  should  be  chosen  for  the  comparative 
experiment. 
12  (a).  Place  each  of  the  above-mentioned  deposits  in  a  thin  weighed 
