380 
VARIETIES. 
ice.  This  discordance  is  probably  due  to  the  difficulty  which  exists  in  the 
way  of  adapting  the  ordinary  methods  of  experiment  to  this  body  Avithout 
introducing  sources  of  error. 
M.  L.  Dufour  has  endeavored  to  solve  the  problem,  by  finding  a  liquid 
in  which  the  ice  would  float  in  equilibrium.  By  ascertaining  the  specific 
gravity  of  that  liquid,  the  required  result  could  of  course  be  obtained.  The 
fluidemployed  by  M.  L.  Dufour  consisted  of  a  mixture  of  alcohol  and  water, 
cooled  down  to  — 8°  or — 10°  Cent.  At  this  low  temperature  the  solution 
of  the  ice  takes  place  with  extreme  slowness,  a  point  which  it  is  necessary 
to  ensure.  By  employing  the  co-efficient  of  dilatation,  the  results  are  readily 
corrected  to  zero. 
M.  Dufour  made  twenty-four  determinations,  the  results  of  which  were 
comprised  between  0.91G2  and  0.9212,  given  a  mean  of  0.9175.  Great  care 
was  of  course  necessary  in  the  selection  of  the  ice,  to  avoid  the  presence  of 
air  bubbles  or  impurity  of  any  kind.  M.  Dufour  used  artificially  frozen 
distilled  water,  which  had  been  previously  well  boiled. — London  Pharm. 
Journ.  Oct.  18G0. 
Blistering  Paper. — Take  of  Cantharidin.,  ^j.  ;  White  Wax,  3j.  ;  Olive 
Oil,  3v.  Melt  together.  With  a  brush,  paint  it  over  some  white  bibulous 
paper,  and  hang  up  to  dry  in  a  current  of  air.  Take  a  piece  of  pink  paper 
of  the  form  and  size  required,  the  under  colored  side  paint  over  with  a  weak 
solution  of  india-rubber;  cut  the  cantharidin  paper  the  form  and  size 
(less  a  margin)  of  the  pink  paper,  and  while  the  india-rubber  solution  is 
still  sticky  place  it  on,  and  when  dry  roll  it  up.  It  is  unafiected  by  damp, 
and  blisters  with  certainty.  Before  applying,  the  blister  should  be  held 
over  the  steam  of  hot  water. —  London  Pharm.  Journ.  Oct.  1860. 
Cement  for  Mending  China,  &c. — Take  of  isinglass  two  drachms,  sprinkle 
it  with  water  and  allow  it  to  stand  until  softened,  then  add  as  much  proof 
spirit  as  will  rather  more  than  cover  it,  and  dissolve  with  a  moderate  heat. 
Take  of  gum  mastic  one  drachm,  dissolve  it  in  two  or  three  drachms  of  rec- 
tified spirit.  Mix  the  two  solutions,  and  stir  in  one  drachm  of  gum  am- 
moniacum,  previously  reduced  to  a  fine  powder  and  rubbed  down  with  a 
little  water.  Evaporate,  if  necessary,  in  a  water-bath  to  a  proper  consist- 
ence. Keep  the  cement  in  a  bottle.  When  required  for  use  plunge  the 
bottle  in  warm  water,  and  apply  the  cement  with  a  stick  or  small  hard 
brush  to  the  china  previously  warmed.  Compress  the  pieces  firmly  together 
until  cold,  taking  care  to  make  the  contact  perfect,  and  using  a  very  thin 
layer  of  cement.  When  properly  applied,  the  cement  is  almost,  if  not  quite, 
as  strong  as  the  china  itself,  unless  exposed  to  the  combined  action  of  heat 
and  moisture. 
Another  cement,  useful  for  many  purposes,  may  be  made  by  dissolving 
isinglass  in  glacial  acetic  acid,  and  reducing  it  to  the  consistence  of  thin 
