16 
Chemical  Notes. 
(  Am.  Jour.  Pharm. 
I      Jan.,  1871. 
CHEMICAL  NOTES. 
By  Professor  Samuel  P.  Sadteer,  Ph.D. 
Inorganic  Chemistry. —  On  the  Specific  Gravity  of  the  Perma- 
nent Gases  at  High  Temperatures. — As  a  result  of  the  recent  experi- 
ments of  Victor  and  Carl  Meyer,  and  of  Crafts  and  Troost,  on  the 
specific  gravity  of  chlorine,  bromine,  and  iodine  at  high  temperatures, 
Messrs.  Troost  and  Berthelot  have  expressed  the  opinion  that  the  pre- 
valent view  of  the  possession  of  uniform  coefficients  of  expansion  by 
the  permanent  gases  would  have  to  be  given  up.  Victor  Meyer  has 
just  determined  the  specific  gravity  of  hydrogen  at  the  highest  tempe- 
rature attainable,  and  finds  that  it  is  perfectly  regular  and  normal  even 
at  these  high  temperatures.  He,  therefore,  does  not  share  the  opinions 
of  Messrs.  Troost  and  Berthelot,  but  enumerates  the  following  gases 
and  vapors  that  possess  a  regular  coefficient  of  expasion  even  at  the 
highest  attainable  temperatures : 
Tellurium  (Deville  and  Troost),      .  .    Nitrogen,  "] 
Sulphur  (Deville  and  Troost;  V.  &  C.  Meyer),  Oxygen,  | 
Hydrochloric  Acid, .  Mercury,  [ 
Carbon  dioxide,      ^['^rcuii,),  .  .         Arsenious  Oxide,  j  *^ 
Hydrogen  (V.  Meyer  and  H.  Ziiblin).  J 
— Ber.  tier  Chem.  Ges.,  xiii,  p.  2019. 
Atomic  Weight  and  Equivalence  of  Beryllium. — The  question  of 
the  equivalence  of  Beryllium  and,  of  course,  with  this  the  matter  of 
its  true  atomic  weight  is  again  the  subject  of  considerable  controversy. 
Berzelius  considered  its  oxide  to  be  Be203,  and  this  was  generally  con- 
ceded until  Mendelejeff^s  classification  of  the  elements  put  Beryllium  in 
the  class  of  dyads,  making  its  oxide  BeO,  and  its  atomic  weight  9*2 
instead  of  13*6  as  previously  regarded.  So  strong  has  the  belief  in 
this  law  become  among  chemists  that  when  Prof.  Emerson  Reynolds, 
some  two  years  ago,  made  a  determination  of  the  specific  heat  which 
apparently  established  the  atomic  weight  9*2  and  the  oxide  as  BeO  it 
was  almost  universally  accepted.  The  Swedish  chemists,  Nilson  and 
Petterson,  very  shortly  afterwards  re-determined  the  specific  heat,  taking 
much  more  thorough  precautions  against  error,  and  gave  as  their  result 
an  atomic  weight  of  13*65  and  Be203  as  the  formula  of  the  oxide. 
Their  results  Avere  attacked  by  Prof.  Lothar  Meyer  and  others,  who 
still  adhere  to  their  belief  in  the  formula  BeO  largely  on  theoretical 
grounds.  Nilson  and  Petterson  have  now  gone  over  the  whole  ground 
again  and  show  that  their  former  results  are  confirmed  and  present  new 
