VARIETIES. 
5T1 
1.  Whether  the  property  of  precipitating  the  lime  is  due  to  the  pure 
charcoal,  or  to  its  earthy  ingredients, — or 
2.  To  atmospheric  carbonic  acid,  as  condensed  in  the  pores  of  the  bone- 
black  ; — 
3.  What  quantity  of  lime  may  be  taken  up  by  the  bone-black  ; — and 
4.  What  proportion  of  the  lime  held  in  solution  is  removed  from  it  by 
varying  proportions  of  bone-black. 
The  answers  to  which,  so  far  as  proved  by  my  experiments,  are  as 
follow  : 
The  earthy  ingredients  of  bone-black  contribute  in  no  wise  to  its  proper- 
ty of  absorbing  lime. 
This  property,  however,  is  not  due  to  the  pure  animal  coal,  but  to  the  con- 
densed carbonic  acid,  and  hence  the  power  of  removing  the  lime  is  in  di- 
rect proportion  to  the  amount  of  carbonic  acid  absorbed  in  its  pores. 
Freshly  calcined,  this  property  is  but  slightly  developed,  but  increases 
distinctly  when  the  charcoal  is  exposed  to  the  action  of  the  atmosphere  or 
to  carbonic  acid,  and  if  to  the  former  under,  favorable  circumstances,  it 
reaches  its  maximum  in  less  than  ten  days. 
Not  more  than-three  fifths  or  two-thirds  of  the  lime  held  in  solution  can 
be  precipitated  by  bone-black  under  the  most  favorable  circumstances. 
The  largest  amount  of  lime  absorbed  by  the  charcoal  amounted  to  44  per 
cent,  of  its  weight  which  is  equal  to  3-45  per  cent,  of  condensed  carbonic  acid. 
In  connexion  with  these  experiments,  Mr.  Anthon  noticed  the  forma- 
tion of  formic  and  hydrocyanic  acid  in  thoroughly  purified  animal  char- 
coal, which  had  been  kept  for  four  years  in  a  not  very  tightly  closed  bottle, 
as  well  as  the  absorption  of  a  large  proportion  of  water,  the  loss  of  this 
charcoal  by  heating  amounting  to  as  much  as  sixteen  percent. — American 
Druggists*  Circular  and  Chemical  Gazette^  from  Dingier* s  Journal. 
Another  neio  Alkali  Metal. — Whilst  investigating  the  new  metal  ccesium, 
Bunsen  has  lately  discovered  another  metal,  which  seems  to  resemble  po- 
tassium as  closely  as  coesium  does.  It  has  a  very  high  atomic  weight,  its 
hydrate  is  deliquescent  and  highly  caustic,  its  carbonate  is  strongly  alka- 
line, and  its  nitrate  anhydrous  like  nitrate  of  potassa,  but,  unlike  that  salt 
its  crystalline  form  is  hexagonal.  It  was  obtained  from  the  saline  residue 
from  44,000  kilogrammes  of  Diirokheim  water,  and  subsequently  from 
lepidolite. —  Chemist  and  Druggist. 
Platinum  Coating  for  Porcelain  Crucibles. — Eisner  gives  the  following 
[Eisner* s  Chem.  Tech,  Mittheilungen,  1859-60,  s.  124)  as  a  method  by  which 
a  strong  covering  of  metallic  platinum  may  be  given  to  porcelain  vessels. 
Platinum-black  is  rubbed  up  with  oil  of  turpentine,  and  the  mixture  is 
painted  over  the  object  to  be  coated,  made  red-hot.  The  vessel  coated  is 
then  enclosed  in  a  capsule,  and  well  burnt  in  a  furnace,  after  which  it  will 
be  found  perfectly  covered  with  a  strongly  fixed  covering  of  metallic 
platinum. 
