ON  THE  VOLATILITY  OF  MERCURY,  ETC. 
427 
The  tantalite  from  Tammela,  which  Von  Kobell  terms  dianite, 
has  a  specific  gravity  of  5-5 — while  the  other  tantalites  vary  in 
density  from  7-06  to  7-5.  The  streak  of  dianite  is  dark  grey, 
while  that  of  the  tantalites  from  Tammela  is  dark  brown  red. 
Before  the  blowpipe,  dianite  exhibits  no  sensible  difference  from 
the  tantalite  of  Kimeto. 
H.  Rose,  to  whom  Von  Kobell  sent  a  specimen  of  dianic  acid 
for  examination,  considered  it  probable  that  the  peculiar  reac- 
tions of  this  substance  might  be  due  to  the  presence  of  tungstic 
acid.  Von  Kobell  has,  however,  shown  by  special  experiments, 
that  this  is  not  the  case.  In  conclusion,  the  author  recommends 
those  who  desire  to  repeat  his  experiments,  to  employ  the  same 
proportions  of  water,  acid,  etc.,  of  which  he  himself  made  use, 
and  for  the  details  of  which  we  must  refer  to  the  original  paper. 
— Sittiman's  Journal,  from  Bull,  der  Acad,  der  Wissenschaften, 
March  10th,  1860,  (Munich). 
NOTE  ON  THE  EXTENT  TO  WHICH  MERCURY  VOLATILIZES 
ALONG  WITH  THE  VAPOR  OF  WATER  AT  100°  C. 
By  J.  W.  Mallet. 
In  Berzelius'  Traits  de  Chimie  it  is  stated  that  Stromeyer 
drew  attention  to  the  fact  of  the  evaporation  of  mercury  in  con- 
siderable quantity  at  60Q  to  80°  C.  with  the  vapor  of  water,  the 
more  volatile  substance  carrying  with  it  the  less  volatile,  as  in 
the  case  of  a  solution  of  boracic  acid  when  heated. 
This  fact  does  not  seem  to  have  been  very  generally  noticed 
by  the  compilers  of  chemical  text-books  in  treating  of  the  his- 
tory of  mercury,  though  it  was  always  stated  that  the  metal  is 
capable  of  volatilizing  to  a  very  slight  extent,  even  when  alone, 
at  the  common  temperature  of  the  atmosphere.  Some  doubt  too 
would  seem  to  have  been  thrown  upon  Stromeyer's  observation 
by  the  experiments  made,  under  peculiar  conditions,  by  Fres- 
enius,  and  reported  by  him  in  the  appendix  to  his  treatise  on 
quantitative  analysis.  It  was  found  that  6-4402  grm.  of  mer- 
cury, covered  with  a  considerable  quantity  of  water,  and  heated 
to  the  boiling  point  of  the  latter  for  a  quarter  of  an  hour,  lost 
but  -0001  grm.,  while  exposure  to  the  air  at  summer  heat  for  six 
days  produced  a  further  loss  of  «0005  grm. 
