ON  SOME  CEMENTS. 
457 
From  its  properties  and  its  composition,  it  takes  its  place  be- 
tween glucose  and  dextrine,  or  between  sugar  and  gum,  for 
C24H23Q23  C12H12012  +  Cl2HU0U 
Glucose.  Dextrine, 
and,  like  glucose,  it  is  composed  of  fecula  and  water. — Chemist ^ 
June,  1857,  from  Journal  fur  Praktische  Qhemie. 
ON  SOME  CEMENTS. 
By  Edmund  Davy,  F.  R.  S.,  M.  R.  I.  A.,  F.  C.  S.  L.,  &c. 
My  attention  has  been  directed  to  make  some  simple  cements, 
which  may  admit  of  useful  and  ready  application. 
Gutta  percha,  as  is  well  known,  is  itself  an  admirable  cement 
for  certain  purposes,  when  softened  by  hot  water  or  by  a  moder- 
ate degree  of  heat;  and  it  has  been  used  in  making  other 
cements ;  but  I  am  not  aware  of  any  cement  described  in  which 
it  forms  a  part :  its  high  commercial  value  is  an  obstacle  to  its 
application  in  many  cases  where  it  could  be  employed  with  ad- 
vantage. 
Gutta  percha,  though  readily  adapted  to  an  almost  endless  varie- 
ty of  uses,  is,  however,  not  easily  rendered  fluid  when  alone,  and 
hence  is  not  quite  manageable  enough  for  certain  purposes, 
I  have  made  many  experiments,  using  different  proportions  of 
gutta  percha  with  pitch,  rosin,  wax,  &c,  with  a  view  to  form 
useful  cements.  In  the  present  communication  I  purpose  to 
notice  only  one  cement,  which  I  made  by  melting  in  an  iron 
saucepan. 
Two  parts  by  weight  of  common  pitch,  and  adding  to  it  one 
part  by  weight  of  gutta  percha,  stirring  and  mixing  them  well 
together  until  they  were  completely  incorporated  with  or  united 
with  each  other,  formed  a  homogeneous  fluid,  which  may  be  used 
in  this  state  for  many  purposes,  but  which,  on  account  of  the 
facility  and  tenacity  with  which  it  adheres  to  metals,  stones, 
glass,  &c,  I  found  convenient  to  pour  into  a  large  basin  of  cold 
water,  in  a  thinner  or  thicker  stream,  or  as  a  cake.  In  this 
state,  while  warm,  it  is  quite  soft,  but  may  be  soon  taken  up  out 
of  the  water  and  drawn  out  into  longer,  or  pressed  into  shorter, 
pieces,  or  cut  or  twisted  into  fragments,  which  may  again  be 
readily  re-united  by  pressure. 
