EXAMINATION  OF  THE  CHRYSOMELA  iENEA. 
525 
monia,  gray,  black,  or  brown  shades  may  be  obtained  at  will. 
Salts  of  copper  and  ferrocyanide  of  potassium  give  coppery 
tints,  &c.  When  porous  limestones,  and  other  bodies  of  analo- 
gous composition,  are  boiled  in  solutions  of  metallic  sulphates 
with  insoluble  oxides,  an  evolution  of  carbonic  acid  takes  place, 
accompanied  by  a  fixation,  at  a  considerable  depth  in  the  stone, 
of  the  metallic  oxides,  which  enter  into  an  intimate  combination 
with  the  sulphate  of  lime.  When  the  oxides  are  colored,  very 
pure  tints  are  obtained  in  this  manner.  With  sulphate  of  iron, 
rusty  tints  of  greater  or  less  depth  are  produced,  according  to 
the  strength  of  the  solutions  ;  with  sulphate  of  copper  the  stone 
receives  a  fine  green  tint ;  sulphate  of  manganese  gives  a  brown, 
and  a  mixture  of  the  sulphates  of  copper  and  iron  a  chocolate 
color.  The  author  has  also  experimented  with  other  sulphates, 
and  with  mixtures  of  them.  The  affinities  which  cause  these 
reactions  are  so  powerful,  that  with  some  sulphates,  such  as  that 
of  copper,  the  oxides  are  so  completely  absorbed,  that  after  boil- 
ing with  an  excess  of  chalk,  no  appreciable  trace  of  them  is  left 
in  the  solution.  In  operating  upon  mixtures  of  sulphate  of  cop- 
per and  iron  or  manganese,  the  oxides  of  iron  and  manganese  are 
the  first  to  be  precipitated.  The  sulphates  with  colorless  oxides 
furnish  analogous  results,  as  does  also  biphosphate  of  lime. 
In  most  cases,  in  order  to  employ  tinted  stones  in  building  or 
in  the  formation  of  mosaics,  it  will  be  advisable  to  increase  their 
hardness  by  silicatization.  The  same  will  apply  to  shells,  white 
coral,  &c,  which  may  be  colored  by  the  same  processes,  by  ope- 
rating at  different  pressures. 
The  double  sulphates  formed  while  penetrating  into  the  stone5 
enter  into  its  composition,  and  increase  its  hardness  to  such  an 
extent,  that  by  the  employment  of  certain  sulphates,  such  as 
that  of  zinc,  silicatization  is  rendered  less  necessary. — Chem. 
Cfaz.,from  Comptes  Hendus,  June  25,  1855. 
CHEMICAL  EXAMINATION  OF  THE  CHRYSOMELA  MNEA. 
By  J.  B.  Enz. 
In  the  year  1850,  Liebig  made  the  observation  that  the  larvse 
of  Chrysomela  Populi  contains  salicylous  acid.  Schneider  has 
noticed  the  occurrence  of  this  acid  in  larvae  collected  upon  wil- 
