30  New  Use  for  Sulphurous  Acid.  {k^lm^ 
require  no  attendance  from  within.  The  charcoal  is  introduced 
through  an  aperture  in  the  roof  into  a  reservoir  at  the  top  of  the  house  ; 
a  closet  on  each  floor  draws  on  this  source  of  supply,  and  the  whole 
of  the  product  is  discharged  in  a  dry  deodorized  state  into  a  cemented 
vault  in  the  basement  story  of  the  house. 
The  reservoir  need  only  be  replenished,  and  the  vault  emptied,  once 
a  year.  The  manure  removed  can  scarcely  be  distinguished  from 
cinders  by  an  ordinary  observer,  and  it  is  equally  inoffensive. 
The  value  of  the  material  removed  is  about  one  shilling  per  cwt., 
or  eight  shillings  per  head  per  annum.  The  household  has  the  char- 
coal and  the  material  removed  without  cost.  A  company  called 
"  The  Nitro-Carbon  Manure  Company  (Limited),"  has  been  formed 
in  Glasgow,  to  collect  and  treat  the  manure,  and  supply  the  char- 
coal.— Med.  Press  and  Circ,  Nov.  15,  1871. 
NEW  USE  FOR  SULPHUROUS  ACID. 
The  action  of  sulphurous  acid  upon  phosphates  has  been  recently 
studied  by  B.  W.  Gerland,  and  he  suggests  certain  practical  results 
that  appear  to  us  to  be  worthy  of  attention.  Aqueous  sulphurous 
acid  does  not  decompose  the  phosphates  in  a  way  to  liberate  the  phos- 
phoric acid,  but  it  transforms  them  into  soluble  modifications  by  the 
production  of  double  salts.  The  triple  phosphate  of  lime,  known  as 
bone  phosphate  or  the  mineral  apatite,  is  at  once  attacked  by  aqueous 
sulphurous  acid,  and  the  concentrated  solution  at  60°  Fahr.  is  decom- 
posed into  three  different  salts — the  mono  and  bi-basic  phosphate  of 
lime  and  sulphite  of  lime — and  if  these  salts  be  evaporated  in  rari- 
fied  air  with  alcohol,  a  series  of  interesting  salts  are  produced.  If 
these  solutions  be  rapidly  heated  to  boiling  under  the  ordinary  pres- 
sure of  the  atmosphere,  a  new  crystaline  salt,  a  double  phosphate  and 
sulphite  of  lime  is  produced,  which  is  said  to  be  quite  permanent,  and 
capable  of  an  extensive  application  as  a  disinfectant  and  fertilizer. 
The  chief  interest  attaching  to  Gerlands's  research  is  the  discovery  of 
a  new  way  of  treating  the  insoluble  phosphates.  We  say  new,  because 
although  the  proposition  was  made  some  years  ago  to  use  sulphurous 
acid  in  the  manufacture  of  phosphorus,  no  one  has  thought  of  apply- 
ing the  method  to  the  decomposition  of  the  mineral  phosphates.  We 
are  by  no  means  certain  that  apatite  or  bones  can  be  economically  de- 
composed in  this  way,  but  it  would  be  well  worth  trying,  as  the  sul- 
