110 



Scientific Proceedings, Royal Dublin Society. 



(of about 2 sq. cm. aperture) from the reservoir into the partially exhausted 

 tubes. In carrying out an experiment, the reservoir was exhausted to about 

 half an atmosphere; 10 c.c. of ether were then allowed to enter along with 

 air to restore the pressure to that of the atmosphere. The wide tube, Ex.T., 

 together with the connecting tube, were then exhausted to the pressure of a 

 few cm. of mercury. The tap T was then turned quickly, so as to allow a 

 sudden rush of the air-ether mixture into the exhausted tubes. In the initial 

 experiments the tap was turned by hand, but afterwards an arm was attached 

 to tlie tap, and ari-anged to bo rapidly rotated by a strong spring on releasing 

 a trigger. This ensured tliat in different experiments the tap was opened at 

 approximately the same rate. When tlie expansion took place, a blue flame 

 was observed to start at the end of the wide tube remote from the reservoir ; 

 this flame travelled up the wide tube and sometimes developed into an 

 explosion strong enough to blow the tubes apart, and even at times to shatter 

 them. 



Ex T. 



C,T. 



TAP 



TO PUMP 



Fin. 1. — Shnwing tlie app.niatiis with wliieh tlie effects connected with the .«udclen expansion 

 of a mixture of air and ether uere first studied. 



We found it convenient to join up the apparatus with rubber corks and 

 plasticine, and the end I) of the wide tube was usually closed with a glass or 

 metal plate fastened on with plasticine. In this way it was easj' to repeat 

 the observations quickly, and to avoid having the apparatus broken when 

 explosions occurred. 



The flame often ti'avelled down the wide tube without any explosion 

 taking place. Again, when the conditions were not such as to produce a 

 visible flame, the smell of the gas remaining in the tube after the experiment 

 often indicated that slight combustion had taken place. Sometimes the flame 

 passed into the connecting tube, and in repeating the exf)erimeiit it is prudent 

 to close the tap T as soon as ignition has been observed, in order to avoid a 

 serious explosion by the ignition of the ether-air mixture in the reservoir. 



The investigation into the nature and cause of these ignition effects may 

 be described under three headings : — 



A. Experiments with ether-air mixtures expanding into glass tubes, 

 in order to study the phenomenon generally. 



