VARIETIES. 
467 
being  suspected  to  be  below  the  proper  quantity,  it  was  examined  thus : — 
100  grs.  dissolved  in  the  least  possible  quantity  of  distilled  water,  the  so- 
lution filtered  from  a  small  quantity  of  dirt  (!),  the  filter  carefully  washed, 
and  the  filtrate  precipitated  by  a  very  small  excess  of  ammonia.  The  pre- 
cipitate was  washed  as  much  as  was  safe  with  water  containing  a  little  am- 
monia ;  it  was  then  dried  on  the  water-bath  at  212°.  After  being  exposed 
to  this  temperature  for  some  time,  it  was  observed  that  the  precipitate,  in- 
stead of  melting  to  the  paper  as  quinine  does,  remained  in  the  form  of  a 
powder  ;  it  was  therefore  weighed,  and  found  to  be  10-4  grs. ;  on  digestion 
in  the  cold  with  ether,  this  wag  reduced  to  5-1.  The  portion  dissolved 
proved  on  examination  to  be  quinine  ;  and  the  portion  separated  by  the  fil- 
ter, as  was  suspected  from  its  infusibility  at  212°,  turned  out  to  be  cincho- 
nine. 
The  scales  therefore  consisted  of — 
Citrate  of  sesquioxide  of  iron  and  ammonia    .        .  89-6 
Quinine        .......  5-3 
Cinchonine  ......  5-1 
The  per-centage  of  quinine  paid  for  by  the  pharmaceutist  was  12.5  per 
cent. —  Chemical  Gazette,  July,  1853. 
Photography  on  Stone.  By  MM.  Barreswil  and  Lemercier. — The  pro- 
cess proposed  by  the  authors,  consists  in  preparing  a  negative  on  paper, 
and  then  producing  a  positive  picture  on  lithographic  stone.  The  negative 
is  obtained  by  any  method,  the  most  rapid  being  preferable.  The  positive 
is  produced  by  a  fatty  or  resinous  coating  laid  on  the  stone,  and  capable  of 
being  rendered  soluble  in  some  solvent  by  the  action  of  light  (and  perhaps 
of  oxygen.)  The  negative  is  laid  upon  the  lithographic  stone  thus  pre- 
pared, and  covered  with  a  glass  plate  ;  the  whole  is  then  exposed  to  the  sun, 
the  stone  washed  with  the  solvent,  and  then  treated  by  the  ordinary  pro- 
cesses of  lithography.  The  authors  have  hitherto  employed  asphaltum  for 
coating  the  stone,  and  sulphuric  ether  as  the  solvent.  They  expect  in  this 
manner  to  reproduce  engravings,  lithographs,  &c. — Chemical  Gazette,  from 
Comptes  Eendus,  May  16,  1853,  p.  878. 
On  the  Preparation  of  Lakes  by  means  of  Chloride  of  Antimony. — Chlo- 
ride of  antimony,  which  is  to  be  met  with  in  commerce  under  the  name  of 
Liquor  Stibii  muriatici,  may,  according  to  a  recent  observation  of  Prof. 
Lampadius,  be  very  well  employed  in  the  preparation  of  several  lakes.  By 
dropping  it  into  decoction  of  Pernambuco-wood,  madder,  Campeachy-wood, 
Quercitron-wood,  and  several  other  coloring  matters,  lakes,  some  of  which 
are  very  fine,  are  produced. 
From  the  infusion  of  cochineal  in  liquid  ammonia,  prepared  in  the  cold, 
when  a  little  pure  vinegar  is  added  to  it,  a  large  quantity  of  lake  is  obtained, 
which  does  not  yield  greatly  in  beauty  to  carmine. —  Chemical  Gazette,  from 
Schweiz.  Gewerbeblatt,  vol.  xi.  p.  127. 
