258 
ON  CHEMISTRY  APPLIED  TO  THE  ARTS. 
drying  it,  and  treating  it  with  ether  to  remove  fatty  matters.  I 
cannot  leave  this  subject  without  remarking  on  the  extraordinary 
stability  of  this  animal  substance,  for  it  has  been  found  in  the 
bones  of  man  and  animal  after  many  centuries,  and  even  in  small 
quantities  in  fossil  bones. 
The  fatty  matter  of  bones  is  made  useful  in  the  manufacture  of 
soap,  railway  grease,  and  in  other  purposes  ;  it  is  obtained  by 
taking  fresh  bones  (as  bones  which  have  been  kept  a  long  time 
will  not  yield  their  grease  easily)  and  placing  the  spongy  parts, 
or  ends  of  the  bones  (where  most  of  the  fatty  matter  exists)  in 
large  boilers  filled  with  water,  which  is  then  carried  to  the  boil, 
when  a  part  of  the  osseine  is  converted  into  gelatine,  and  the 
fatty  matter  liberated,  which  rises  to  the  surface,  and  is  easily  re- 
moved. The  bones  thus  treated  are  called  boiled  bones,  and  re- 
ceive many  important  applications,  to  which  your  attention  will 
be  called  in  a  few  minutes.  Benzine  and  bisulphuret  of  carbon 
have  been  used  as  substitutes  for  water  in  the  above  operation, 
but  the  advantages  do  not  seem  to  have  been  sufficient  to  lead  to 
their  general  adoption. 
Mineral  Matter  of  Bones. — These,  as  the  foregoing  tables 
show,  are  chiefly  represented  by  phosphate  and  carbonate  of  lime. 
The  immortal  Berzelius  was  the  first  to  establish  the  fact  that 
phosphate  of  lime  was  the  only  substance  possessing  the  proper- 
ties necessary  for  the  formation  of  bone,  owing  to  the  extremely 
simple  chemical  reactions  which  cause  the  soluble  phosphates  to 
become  insoluble.  Let  us  trace  shortly  the  sources  from  whence 
we  derive  the  large  proportion  of  phosphate  of  lime  which  exists 
in  our  frames.  Several  of  our  most  eminent  chemists  have 
proved  the  existence  of  phosphorus  in  sedimentary  and  igneous 
rocks,  and  the  important  part  played  by  phosphorus  in  nature 
cannot  be  better  conveyed  to  your  minds  than  by  this  extract 
from  Dr.  Hofmann's  learned  and  valued  Report  on  the  Chemical 
Product  in  the  Exhibition  of  1862: — "  Large  masses  *of  phos- 
phorus are,  in  the  course  of  geological  revolutions,  extending 
over  vast  periods  of  time,  restored  from  the  organic  reigns  of 
nature  to  the  mineral  kingdom  by  the  slow  process  of  fossilisa- 
tion ;  whereby  vegetal  tissues  are  gradually  transformed  into 
peat,  lignite,  and  coal ;  and  animal  tissues  are  petrified  into  co- 
prolites,  which  in  course  of  time  yield  crystalline  apatite.  After 
