ON  RUBIDIUM  AND  CESIUM. 
67 
This  per  centage  may  be  converted  into  Revenue  proof  spirit 
by  rule  of  three  sum,  thus: — 
Ale.      Wat.  Ale. 
As  49  :  51  :  :  17  =  17*69  water. 
17  alcohol. 
Proof    .        .  34-69 
Qhem.  News  London,  Oct.  19,  186 1. 
ON  RUBIDIUM  AND  CAESIUM. 
Br  M.  Bunsen. 
In  addition  to  the  facts  which  we  have  already  published  on 
the  subject  of  these  two  metals,  discovered  by  M.  Bunsen,  by 
means  of  spectrum  analysis,  we  add  the  following  : — 
The  equivalent  of  rubidium  is  85-36  (H=  1),  more  than 
double  than  of  potassium  ;  metallic  rubidium  is  even  more  elec- 
tro-positive than  potassium, — -it  amalgamates  easily  and  decom- 
poses water  in  the  cold. 
The  hydrate  of  rubidium,  RJbO.HO-}-Aq,  is  soluble  in  all 
proportions  in  water  and  alcohol.  When  heated  it  fuses  in  its 
water  of  crystallization,  becoming  reduced  to  the  state  of 
RbO.HO,  which  is  fusible  at  a  higher  temperature  without  losing 
weight.  It  acts  like  caustic  potash,  attracting  water  and  car- 
bonic acid  from  the  air,  and  dissolves  in  water  with  disengage- 
ment of  heat. 
The  carbonate,  RbQ.C02-f-Aq,  forms  ill-defined  crystals,  of 
strong  alkaline  reaction,  fusible  by  heat  in  their  water  of 
crystallization,  and  becoming  anhydrous.  This  salt  is  fusi- 
ble, deliquescent,  and  attracting  from  the  air  a  second  equival- 
ent of  carbonic  acid.  The  aqueous  solution  saponifies  the  skin 
exactly  like  carbonate  of  potash. 
The  bicarbonate,  Rb0.2CO-|-HO,  forms  brilliant  prisms,  un- 
alterable in  the  air,  having  a  slight  alkaline  reaction,  and  a, 
saline  taste  not  at  all  caustic. 
The  nitrate,  RbO.N05,  does  not  crystallize  in  rhombohedral 
prisms  like  saltpetre,  but  in  prisms  with  a  hexagonal  base, 
which  is  a  second  form  of  nitrate  of  potash.  It  dissolves  in  5 
parts  of  water  at  0°  C,  and  in  2-3  parts  of  water  at  10°  C. 
