304 Mixter — Products of the Explosion of Acetylene. 



Experiment 53. — Gas, 99 per cent of acetylene ; pressure, 

 2300 mm . The electrodes were 4 mm apart. Two estimations of 

 acetylene in the gas taken at 3 atmospheres gave each 1*5 per 

 cent, and when the pressure in the apparatus had fallen nearly 

 to that of the atmosphere the portions tested were found to 

 contain 1*9 and 1*8 per cent of acetylene. 



The next two experiments were made in the iron U-tube in 

 order to find the effect that the expansion accompanying the 

 explosion has on the formation of hydrocyanic acid. The mix- 

 tures of acetylene and nitrogen were kept for a day over a 

 solution of ferrous sulphate in which was suspended ferrous 

 hydroxide. 



Experiment 53. — About 1%5 liters, measured at atmospheric 

 pressure, of gas containing 15 per cent of nitrogen were used. 

 The mixture was sparked when under a pressure of 2*5 atmos- 

 pheres. The residual gas contained l - 25 per cent of acetylene. 

 800 cc of it were passed through a solution of potassium 

 hydroxide. This was then titrated with a decinormal solution 

 of silver nitrate, requiring - 4 cc to produce a permanent pre- 

 cipitate, a result not indicating satisfactorily the presence of 

 cyanides. 



Experiment 54- — The mixture contained 13*5 per cent of 

 nitrogen. Two liters of gas were taken and subjected to a 

 pressure of 2*5 atmospheres. The explosion was prompt. 

 The estimation of acetylene in the residual gas was not satis- 

 factory but it showed there was less than 3 per cent present. 

 1000 cc of the gas left by the explosion were passed slowly 

 through a solution of potassium hydroxide. One drop of a 

 decinormal solution of silver nitrate gave to the solution a 

 permanent brown precipitate. Next, 200 cc of the gas were 

 passed through a solution of potassium hydroxide, made from 

 the metal. Finally a few drops of a solution of ferrous 

 ferric sulphate were added and the mixture was warmed, 

 cooled, and made acid with hydrochloric acid. No prussian 

 blue was formed, a proof that no hydrocyanic acid had been 

 formed. 



These results in the iron U-tube prove conclusively that the 

 large amounts of acetylene and condensation products in the 

 earlier experiments in glass tubes are not attributable to expan- 

 sion at the time of the explosion. 



In order to learn whether the peculiar explosive wave of 

 experiments 27 and 28 of the first paper can be transmitted to 

 gas in a larger vessel and there produce the same effect, the 

 next two experiments were made in the apparatus shown in 

 fig. 2. The tube a is glass and has a diameter of 18 mm . 



