Mixter — Products of the Explosion of Acetylene. 303 



Experiment If.7. — Two liters of a dried mixture of acetylene 

 and nitrogen containing 10 per cent of the latter gas were 

 passed through a combustion tube which was heated to a tem- 

 perature sufficient to decompose the acetylene. The gaseous 

 products were passed through a solution of potassium hydroxide 

 to absorb hydrocyanic acid. But not a trace was found by the 

 prussian blue reaction. The same result was obtained a second 

 time. 



Experiment J/.8. — A mixture of acetylene and air was ex- 

 ploded in an open liter jar. Much soot separated and the flame 

 passed slowly into the jar. No hydrocyanic acid was detected 

 in the products, and none in several repetitions of the experi- 

 ment. 



Experiment 1^9. — The sides of a jar were moistened with 

 strong ammonia water and the air in the jar was mostly dis- 

 placed by acetylene. On applying a flame to the mouth of the 

 jar there was a slight puff and an abundant separation of soot 

 in the jar. Hydrocyanic acid was found in the products of 

 four experiments, and it was also formed rather abundantly 

 when illuminating gas was substituted for acetylene. 



Experiment 50. — Acetylene was passed through concen- 

 trated ammonia water, then through a tube heated to dull red- 

 ness by one burner. Hydrocyanic acid was formed. 



The experiments 19 to 28 described in the first paper (loc. 

 cit.) were made in U-tubes haviug a diameter of IT to 20 mra . 

 The residual gas contained much acetylene and the amount of 

 condensation products was considerable. In order to learn if 

 the character of the products is due to the expansion of the 

 gas when exploded, the next two tests were made in an iron 

 U-tube T'5 cm in diameter. To the ends of this tube were attached 

 the parts a and h of the iron bomb (fig. 1, p. 299). The appa- 

 ratus was designed for observing the effect of explosions under 

 the same conditions as in the bomb except that the gas was not 

 subjected to constant volume. About 50 kilos of mercury 

 were required in the apparatus and 1800 co of dry acetylene 

 measured at atmospheric pressure were used. The U-tube 

 when charged for an explosion was hung in a tank of water in 

 order to cool it quickly after an explosion. When acetylene 

 is fired in such a U-tube the products cool more rapidly 

 than in the bomb. 



Experiment 51. — Gas, 99 per cent of acetylene ; pressure, 

 2060 mm at 18°. The electrodes were 2 mm apart.' The explosion 

 was prompt and the pressure after it was 209T mm at 18°. Two 

 determinations of acetylene in the gas after explosion gave 3 

 per cent. 



