536 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1916. 



aid and rescue classes, thus starting a safety propaganda where it 

 otherwise would not be received. 



NEW FORM or OXYGEN MINE RESCUE APPARATUS. 



After a long period of experiment the Bureau of Mines has devel- 

 oped a new form of oxygen breathing apparatus for use in poisonous 

 or irrespirable atmospheres in mines after fires or explosions. It is 

 called the Gibbs apparatus, after its chief designer, W. E. Gibbs, 

 tngineer of mine-safety investigations, of the bureau. 



In such apparatus, as it is impracticable to compress into a portable 

 tank enough air to supply the breathing needs of the wearer for the 

 hour or two during which he remains in poisonous atmospheres, pure 

 oxygen is used. In general, an oxygen rescue apparatus consists of 

 a small tank of compressed oxygen, a reducing valve through which 

 the oxygen Aoaas to a mouthpiece connected to the breathing bag by 

 flexible tubes, and a receptacle containing caustic soda for absorbing 

 the carbon dioxide from the exhaled air. Valves that open and close 

 at each breath prevent expired air from returning to the lungs before 

 it has passed through the purifier. 



To construct an apparatus of this kind would be relatively simple 

 if it were not for the conditions under which the apparatus is worn. 

 As rescue crews work in the unmapped wreckage following mine 

 accidents, in a presumably irrespirable atmosphere and often in 

 smoke so dense that their electric lamps are of small help, any failure 

 of an oxygen rescue apparatus may mean death to the wearer. 

 Moreover, the labor of exploration and rescue is often arduous, and 

 the apparatus worn must be as light as is consistent with strength 

 and j'^et strong enough to withstand the hard knocks it is sure to 

 receive. It must be mechanically so perfect that it will not fail to 

 function, and yet be so simple that it can be manipulated with 

 safety in the dark and in surroundings that exhaust the wearer both 

 physically and menta]l3^ 



The Gibbs apparatus, developed by the Bureau of Mines, differs 

 from others in the following particulars : 



By means of a new form of reducing vulve the oxygen is supplied 

 to the user at a variable rate which constantly adjusts itself to his 

 immediate demands. 



A new fonn of carbon dioxide absorber keeps the inspired air pure 

 and prevents it from reaching an uncomfortably high temperature 

 during the two-hour standard period of use. 



The pressure gauge, which indicates the available supply of 0x3^- 

 gen, is read by touch. Thirty minutes before the supply is exhausted 

 it rings an alarm. 



