VARIETIES. 
475 
With  the  chloride  of  antimony,  the  presence  of  strychnine,  even  in  a  large 
quantity,  fails  entirely  in  producing  the  violet  tint  with  the  addition  of 
sulphuric  acid  and  bichromate  of  potash. —  CJiem.  Gaz.  JunelQ,  1856. 
Determination  of  Butter  in  Milk.  By  M.  Marchand. — Marchand's 
lactobutyrometer  consists  of  a  straight  glass  tube  as  the  vessel  of  reception, 
which  terminates  in  a  narrower  glass  tube  closed  on  one  side.  Up  to 
19-20ths  of  its  contents  it  is  divided  into  3  equal  parts,  of  which  that  nearest 
the  opening  again  has  its  three  upper  tenths  divided  into  100  parts,  10  of 
which  are  carried  on  beneath  the  line  of  demarcation. 
For  use,  the  first  division  is  filled  with  milk,  to  every  10  cub.  centims.  of 
which  a  drop  of  caustic  soda  is  added  ;  this  is  covered  with  the  same  volume 
of  ether,  the  two  fluids  are  thoroughly  mixed  together,  and  the  last  division 
is  then  filled  with  alcohol  of  spec.  grav.  0-864  to  0-833°,  and  the  whole  well 
shaken  together.  The  instrument  is  then  immersed  in  a  water-bath  of 
109°4  F.,  and  left  there  in  a  vertical  position  until  the  temperature  of  the 
water-bath  has  fallen  to  86°  F.  The  volume  of  fat  which  has  separated  on 
the  surface  is  determined  by  reading  off  the  degrees  which  it  occupies  from 
above  downwards  to  the  lowest  level  of  the  meniscus.  The  corresponding 
weight  of  butter  for  each  kilogramme  is  found  in  a  table. —  Chem.  Gaz. 
July  1,  from  Journ.  de  Chim.  Med.  Nov.  1856. 
On  the  Prevention  of  tlie  Oxidation  of  Metals.  By  H.  Draper. — Those 
familiar  with  electrical  science  are  well  acquainted  with  the  fact  that  zinc 
exercises  positive  relations  with  regard  to  most  other  metals.  In  other 
words,  it  possesses  the  power  of  keeping  them  in  a  negative  state  when  in 
contact  with  them. 
In  this  negative  state  they  are  incapable  of  entering  into  combination 
with  oxygen,  and  this  circumstance  may  be  applied  with  much  advantage 
to  the  prevention  of  the  oxidation  of  machinery,  especially  such  parts  of  it 
as,  in  the  case  of  marine  engines,  are  liable  to  come  in  contact  with  water. 
Many  instances  will  at  once  suggest  themselves  in  which  much  manual 
labor  might  be  saved  by  the  simple  contrivance  of  appending  either  a  ring 
or  slip  of  zinc  to  the  metal  to  be  preserved  bright.  It  would  be  especially 
applicable  in  the  case  of  bayonets  and  rifle  barrels,  and  a  zinc  edging  to  a 
scabbard  would  prevent  the  rusting  of  the  sword. 
I  have  employed  this  method  for  some  years  with  perfect  success  in  the 
ease  of  articles  of  polished  steel,  which,  for  the  sake  of  experiment,  were 
placed  in  precisely  similar  circumstances  with  others  not  so  protected,  and 
retained  their  brilliancy,  while  the  others  became  rapidly  covered  with  a 
thick  coating  of  oxide.  The  useful  properties  of  "  galvanized  iron,"  not 
improperly  so  called,  are  due  to  the  same  cause. — London  Pharm.  Journal. 
The  natural  state  of  Hippuric  Acid. — So  great  differences  exist  in  regard 
to  the  proportions  of  hippuric  acid  contained  in  the  normal  state  in  the 
