Am  Jour.  Pharm. 
April,  1898. 
Formaldehyde. 
199 
simple  problem,  but  in  practice  many  difficulties  were  encountered  ; 
it  was  at  first  thought  that  it  would  only  be  necessary  to  evaporate 
a  quantity  of  the  solution  in  an  open  vessel  placed  over  a  heating- 
lamp  in  the  room,  but  it  was  found  that  when  the  solution  became 
concentrated  by  boiling,  polymerisation  occurred  and  paraldehyde 
was  formed,  thus  rendering  about  70  per  cent,  of  the  formaldehyde 
in  the  solution  inert  and  unavailable.  The  same  result  ensued  when 
formaldehyde  was  evaporated  at  room  temperature. 
Trillat  demonstrated  that  when  the  temperature  was  raised  to  a 
point  considerably  above  that  of  boiling  water,  all  of  the  gas  in  the 
solution  was  given  off  and  rendered  available  for  disinfection.  His 
apparatus  consisted  of  a  strongly-constructed  autoclave  made  of  cop- 
per and  provided  with  a  heating-lamp,  pressure  gauge  and  releasing 
valve.  In  operation  the  solution  of  formaldehyde  was  heated  in  the 
autoclave  until  a  pressure  of  three  atmospheres  was  attained,  when 
the  releasing  valve  was  cautiously  opened  and  the  generated  gas 
was  conveyed  by  a  small  tube  through  the  keyhole  into  the  apart- 
ment. Satisfactory  results  were  obtained  with  this  apparatus,  but 
its  great  weight,  the  length  of  time  required  for  each  disinfection, 
and  its  first  cost  and  the  expense  of  operation  have  prohibited  its 
use  in  many  large  cities  when  a  number  of  disinfections  are  made 
daily.  Many  lamps  designed  to  generate  formaldehyde  directly  from 
methyl  alcohol  have  been  brought  out  from  time  to  time,  but,  owing 
to  the  extreme  delicacy  of  adjustment  required,  and  also  to  the  fact 
that  varying  atmospheric  conditions  render  constant  changes  in 
adjustment  necessary,  none  have  given  satisfactory  results  or  have 
succeeded  uniformly  in  generating  more  than  a  very  small  percent- 
age of  formaldehyde. 
About  two  years  ago  I  was  requested  to  design  a  small  portable 
apparatus  for  house  disinfection.  The  requirements  were  that  it 
was  to  be  inexpensive  in  first  cost  and  in  operation,  and  that  it 
should  be  so  simple  in  construction  and  operation  that  it  could  be 
readily  understood  by  a  person  of  average  intelligence.  After  a 
number  of  partial  failures,  I  have  succeeded  in  designing  this  appa- 
ratus, which  I  think  fills  the  requirements. 
It  consists  of  a  copper  reservoir  capable  of  holding  sufficient  for- 
maldehyde to  effect  ten  or  twelve  disinfections  ;  beneath  this  receiver, 
and  connected  with  it  by  a  tube,  is  a  copper  evaporating  chamber; 
under  this  chamber  is  a  powerful  heating-lamp.    In  operation,  the 
