332 
ACID  PEOOF  CEMENT. 
rated  spontaneously,  or  mixed  with  some  ether,  microscopic' yel- 
low needles  are  obtained.  Rhamnin  has  but  little  taste  ;  it  dis- 
solves in  water,  alcohol,  and  acetic  acid,  sparingly  in  absolute 
alcohol;  scarcely  in  ether  and  chloroform.  The  golden  yellow 
color  of  the  aqueous  solution  changes,  on  exposure,  to  brown. 
The  cold  solution  is  not  affected  by  the  acetates  of  copper,  lead, 
zinc  or  alumina,  the  chlorides  of  tin  and  niercury,  nitrate  of 
silver,  gelatin,  caustic  baryta,  sulphate  of  soda  and  chloride  of 
sodium.  Ferric  chloride  colors  the  solution  olive  green,  nitro- 
prusside  of  sodium,  deep  brown  red ;  chlorinated  lime,  dark  green. 
The  alcoholic  solution  is  precipitated  by  lead  salts. 
Dilute  sulphuric  acid  and  the  above  mentioned  ferment  split 
rhamnin  into  rhamnetin  and  a  gum-like  body  which  reduces 
alkaline  solutions  of  cupric  oxide.  Cloth  upon  which  alum  or 
tin-salt  had  been  used  as  a  mordant  were  not  dyed  by  solution  of 
rhamnin ;  an  intense  color  was,  however,  produced  after  the 
addition  of  a  little  rhamnin  ferment.  Brown  buckthorn  berries, 
which  contain  much  rhamnin,  may  be  used  with  advantage  for 
dyeing  by  the  addition  of  an  infusion  of  the  olive  green  fruit. 
The  author  could  not,  by  boiling,  convert  the  insoluble  rhamnetin 
into  the  soluble  rhamnin,  as  the  statement  of  Kane  seems  to 
indicate. 
It  is  difficult  to  free  the  rhamnin  from  the  last  traces  of  a  nitro- 
genous compound.  On  analysis  the  author  obtained  results 
indicating  a  composition  similar  to  that  of  ruberythrinic  acid  and 
of  quercitrin. — Zeitschr.  f.  Chemie,  1869,  183,  184, /row  Journ. 
/.  prakt.  Chem.  cv,  97. 
ACID  PROOF  CEMENT. 
Mr.  Editor  : — Thinking  that  the  following  suggestion  may  be 
of  use  to  or  improved  upon  by  some  of  the  readers  of  the  Journal 
of  the  Franklin  Institute,  I  offer  it  with  these  ideas  for  what  it 
may  be  worth.  It  frequently  happens  that  the  chemist  requires 
some  means  for  protecting  cork  from  the  destructive  action  of 
vapors  such  as  arise  from  boiling  nitric  acid.  I  think  that  the 
plan  here  mentioned  may  possibly  meet  this  requirement. 
Finding  it  necessary  to  connect  a  glass  tube  with  a  wide-mouthed 
