UREA  AS  A  DIRECT  SOURCE  OF  NITROGEN  TO  PLANTS.  157 
water  for  about  twenty-four  hours,  straining  the  solution,  then 
mixing  with  it  a  warm  solution  of  about  six  ounces  of  gelatin  or 
paste,  and  finally  adding  about  ten  ounces  of  acetate  of  alumi- 
na, mixing  and  straining.  The  meat  is  kept  in  this  bath  for 
about  two  minutes,  being  drawn  and  moved  about  in  it  by  the 
string  ;  it  is  then  taken  out  and  suspended  in  a  current  of  dry 
air  for  about  twenty- four  hours.  The  process  of  immersion,  &c, 
is  repeated  once  or  twice,  as  may  be  considered  desirable. — 
Chemist,  Nov.  1858,  from  the  Journal  of  the  Society  of  Arts. 
ON  UREA  AS  A  DIRECT  SOURCE  OF  NITROGEN  TO  PLANTS. 
By  Charles  A.  Cameron,  M,  D. 
At  the  meeting  of  the  British  Association,  held  at  Dublin  last 
year,  I  read  a  paper,  in  which  I  proved  the  inutility  of  ferment- 
ing liquid  manure  before  applying  it  to  the  purpose  of  fertilis- 
ing the  soil,  and  demonstrated  that  urea,  without  being  convert- 
ed into  carbonate  of  ammonia,  may  be  taken  up  into  the  organ- 
ism of  plants  to  be  used  as  nitrogenous  food.  The  experiments 
detailed  in  this  paper  have  not  been  published  in  extenso  in  the 
Report  of  the  British  Association ;  I  therefore  give  them  here, 
as  well  as  the  results  of  some  other  experiments  of  a  practical 
character,  which  have  since  been  performed  under  my  direction, 
and  which  serve  to  support  the  conclusions  arrived  at  from  the 
earlier  experiments. 
EXPERIMENTS. 
Four  earthenware  basins,  each  two  feet  in  depth  and  two  and 
a-half  feet  across,  were  filled  with  fragments  of  felspar  of  differ- 
ent degrees  of  fineness,  the  coarsest  fragments  being  placed 
lowest.  In  each  of  these  basins  sixty  grains  of  barley  were  sown 
on  the  5th  of  May  (1857).  The  basins  were  then  numbered  1, 
2,  3,  and  4,  and  in  each  was  placed  a  portion  of  an  artificial 
manure,  containing  the  following  substances,  viz  : — 
The  double  silicate  of  potash  and  soda  (soluble),  precipitated 
carbonate  of  lime,  hydrated  sulphate  of  lime,  freshly  precipitated 
phosphates  of  lime  and  magnesia,  and  chloride  of  sodium.  The 
bases  and  acids  of  this  compound,  were  in  such  proportion  as 
nearly  to  correspond  with  the  general  composition  of  the  ash  of 
the  barley  plant. 
