Section 118. Technical rules of evidence or procedure not required

The
  chairman or board in making an investigation or inquiry or conducting  a
  hearing  shall not be bound by common law or statutory rules of evidence
  or by technical or formal rules of procedure, except as provided by this
  chapter; but may make such investigation  or  inquiry  or  conduct  such
  hearing  in  such  manner  as to ascertain the substantial rights of the
  parties. Declarations of a deceased  employee  concerning  the  accident
  shall   be   received   in   evidence  and  shall,  if  corroborated  by
  circumstances or other evidence, be sufficient to establish the accident
  and the injury.