PROPERTIES  OF  SILICATES.     NEW  ANTIDOTES.  433 
silicates  are  modified  by  solution  in  the  colorless  compound 
soluble  silicates — that  of  copper,  for  instance,  in  a  soda  silicate 
of  magnesia,  is  different  from  that  of  its  solution  in  silicate 
of  soda. 
The  above  fact  will,  I  think,  be  sufficient  to  indicate  the  im- 
portance of  a  true  knowledge  of  the  compound  soluble  silicates 
in  geology  and  mineralogy,  and  lead  to  a  more  exact  explanation 
of  the  color  of  a  great  number  of  minerals  and  of  many  of  the 
precious  stones. 
The  silicic  acid  of  the  alkaline  silicates  again  displaces  the 
carbonic  acid  in  carbonates,  even  at  the  ordinary  temperature, 
and  very  rapidly  by  the  aid  of  heat.  This  fact  will  aid  towards 
explaining  the  formation  and  composition  of  many  rocks,  and 
be  a  guide  in  the  production  of  artificial  stones  in  endles3 
varieties. 
As  regards  agriculture,  the  ammonio-silicates  seem  not  only 
to  be  the  most  soluble,  but  also  to  possess  the  greatest  solvent 
powers  of  all  the  alkaline  silicates.  When  we  add  to  the  series 
the  phospho-silicates,  also  highly  soluble,  it  seems  to  me  that  a 
field  of  investigation  is  laid  open  worthy  of  the  highest  science 
of  the  day  in  the  department  of  agricultural  chemistry,  and 
which,  if  followed,  is  likely  to  lead  to  practical  results  of  vast 
importance,  and  to  a  true  solution  of  many  things  that  have 
not  hitherto  been  satisfactorily  explained. 
There  is  still  another  field  open  to  investigation  with  these 
interesting  compounds,  namely,  the  use  of  them  as  antidotes  to 
poisons. 
For  this  purpose  I  would  suggest  the  soda  silicates  of  mag- 
nesia, alumina,  and  lime.  In  case  of  any  poisonous  mineral 
salt  being  taken,  an  instantaneous  precipitation  of  an  insoluble 
silicate  would  occur  in  the  stomach,  and  probably  without  the 
least  injurious  effect  to  the  coats  thereof,  by  prompt  administra- 
tion of  a  diluted  solution  of  any  of  the  above-named  compound 
soluble  silicates,  or  of  a  solution  of  silicate  of  soda  saturated 
with  gelatinous  silica.  It  is  a  question  which  I  have  com- 
menced investigating,  whether  the  alkaloids  may  not  be  ren- 
dered insoluble,  and  therfore  inert,  through  their  means. 
I  am,  &c, 
Bangor,  June  28.  Henry  Ellis. 
28 
