Am*3{ayri£oarm'}  Conservation  and  Chemical  Engineer.  239 
200,000  metric  tons  per  annum,  largely  in  countries  like  Norway, 
Italy,  and  Switzerland  where  cheap  water  power  is  available,  as  well 
as  in  the  United  States  at  Niagara  Falls  and  Sault  St.  Marie.  This 
production,  however,  for  the  time  being  outran  the  demand  for 
carbide  for  acetylene  lighting. 
Relief  from  over-production  by  finding  new  outlets  and  utiliza- 
tions is  always  to  be  preferred  to  closing  of  works  already  in  opera- 
tion, so  chemical  engineers  have  found  new  possibilities  for  calcium 
carbide.  By  far  the  most  important  of  these  is  the  production  from 
calcium  carbide  of  calcium  cyanamide  by  the  action  of  nitrogen  gas, 
as  worked  out  by  Drs.  Frank  and  Caro.  We  have  here  an  exother- 
mic reaction  in  which  nitrogen  is  absorbed  by  the  carbide  with  the 
production  of  calcium  cyanamide  and  carbon.  This  takes  place  at  a 
temperature  of  from  8oo°  to  10000  C,  much  below  that  needed  for 
the  carbide  manufacture.  Not  only  can  all  the  nitrogen  of  this 
cyanamide  be  converted  into  ammonia  by  decomposition  with  steam, 
but  it  is  gradually  decomposed  by  the  chemical  and  bacteriological 
constituents  of  the  soil  into  ammonia,  which  becomes  fixed  by  the 
vegetable  mould  and  is  so  held.  The  cyanamide  is  also  convertible 
into  calcium  cyanide  by  melting  with  fluxes,  into  dicyandiamide  for 
dye-color  manufacture,  into  urea,  guanidine,  and  other  hitherto 
relatively  expensive  organic  compounds.  The  dicyandiamide  is 
already  used  as  a  "  deterrent  "  in  smokeless  powder  manufacture, 
reducing  the  temperature  of  the  explosion  without  diminishing  ex- 
plosive force,  and  the  crude  calcium  cyanamide  with  certain  fluxes 
under  the  name  of  "  ferrodur  "  is  employed  for  case-hardening  of 
iron  and  steel. 
The  statement  is  made  that  the  works  for  the  manufacture  of 
"  nitrolime  "  now  in  operation  or  in  course  of  construction  have 
a  capacity  of  166,000  tons  per  year. 
The  illustrations  of  conservation,  whether  from  the  point  of 
view  of  better  utilization  of  materials,  or  the  production  of  new 
and  varied  products,  or  the  recovery  of  what  were  waste  products, 
could  be  greatly  extended  did  time  allow. 
We  might  refer  to  the  way  in  which  sulphur  recovery  has 
been  worked  out  in  the  alkali  industry,  or  to  the  manganese  recovery 
in  connection  with  the  chlorine  production  from  manganese  dioxide, 
so  that  "  recovered  manganese  "  is  to-day  a  most  valuable  article 
of  commerce.  Or  we  might  note  the  saving  resulting  from  the 
manufacture  of  reclaimed  rubber,  but  these  and  similar  illustrations 
