370       Pennsylvania  Pharmaceutical  Association.  {A^uJguSrt,,T907!:m' 
tion  will  be  slightly  blue  on  account  of  the  copper  which  is  alloyed 
with  coin  silver.  Place  the  solution  in  a  glass  vessel  with  a  curved 
bottom.  Add  a  drop  of  mercury  the  size  of  a  large  pea  and  set 
aside  for  twenty-four  hours  or  place  in  the  window.  An  arbores- 
cent growth  of  mercury  and  silver  amalgam  will  be  produced  which 
may  be  kept  indefinitely. 
Lead  Tree. — Place  in  a  tall  jar  or  wide-mouthed  bottle  a  solution 
made  by  dissolving  4  ounces  of  lead  acetate  in  one  quart  of  water. 
Place  the  vessel  where  it  will  not  be  subject  to  vibration,  and  sus. 
pend  in  it  a  strip  or  cylinder  of  zinc  ;  battery  zinc  answers  the  pur- 
pose very  well.  An  abundant  growth  of  crystalline  spangles  of 
metallic  lead  will  collect  on  the  zinc  within  forty-eight  hours. 
Tin  Tree. — Dilute  commercial  tin  chloride  solution  with  forty 
times  its  bulk  of  water  and  suspend  a  strip  or  pencil  of  zinc  in  it  as 
in  the  case  of  the  lead  tree.  The  growth  will  be  very  similar  to 
that  of  the  lead  tree. 
The  most  striking  growths  that  can  be  obtained  from  purely 
inorganic  substances  are  those  which  are  formed  in  solution  of 
sodium  silicate  in  the  following  manner.  In  the  bottom  of  a  wide- 
mouthed  bottle  or  glass  jar,  distribute  about  an  inch  of  clean  sand. 
Place  on  top  of  it  small  crystals  (from  about  the  size  of  a  pea  to  that 
of  a  hazel  nut)  of  alum,  copper  sulphate,  ferrous  sulphate,  manganous 
sulphate,  chrome  alum,  ammonio.ferric  alum,  magnesium  sulphate, 
calcium  chloride,  lead  acetate  and  nickel  and  ammonium  sulphate. 
It  is  not  necessary  to  have  all  of  these.  Any  one  of  them  will  do, 
but  a  mixture  of  several  gives  more  striking  results.  Having  dis- 
tributed the  crystals  upon  the  sand,  introduce  carefully  enough 
solution  of  sodium  silicate,  made  by  diluting  the  commercial  solu- 
tion with  an  equal  bulk  of  water,  to  cover  the  crystals  with  liquid 
to  a  depth  of  three  or  four  inches.  The  plant-like  growths  will 
begin  immediately,  and  within  twenty-four  hours  will  assume  fan- 
tastic and  interesting  forms. 
Standardization  of  Diphtheria  Antitoxin. 
W.  A.  Pearson. 
A  review  of  the  subject  of  diphtheria  antitoxin  and  the  method 
of  standardization  of  the  antitoxin  is  written  in  a  very  clear  and 
interesting  manner.  Attention  is  called  to  the  necessity  of  keeping 
the  supply  of  antitoxin  under  proper  conditions  in  the  store  so  that 
its  efficiency  may  not  be  impaired. 
