90 



Substance. 



KCI03 



Genei"a'inj 

 Time. 



Volume. 

 lObserved. Calculated. 



SOgins.MnOo .. 

 200 " " .. 

 186 " Silica . 

 500 '• Sand .. 

 120 " MnOj.. 

 65 Venetian red 



250 gms. 

 1000 " 

 930 " 

 500 " 

 600 " 

 325 " 



18.5 



24 



20 



11 



25 



73 Liters. 

 257 " 

 56 " 

 16.7 " 

 137.5 " 

 21.9 " 



74.4 



296.5 



273 



147.5 



177.5 



97.6 



Gas lost. 

 Exploded. 



Gas lost. 



The first column gives the amount and name of substance used; 

 2d, amount of potassium chlorate; 3d, duration of the experiment iu min- 

 utes; 4th, the volume of gas liberated as shovpn by the gas meter; 5th, 

 volume of gas as calculated from mass of potassium chlorate and tem- 

 perature and pressure of gas in the meter; 6th, temperature of gas in 

 meler. 



In tlie third experiment with powdered silica heat was applied stead- 

 ily for twenty-four minutes until suddenly the delivery tube connecting 

 the retort to the calorimeter was blown off and a stream of blazing 

 molten silica was shot a distance of fifteen feet across the room. Upon 

 cleaning the retort it was found that the mass of chlorate and silica 

 had been in a foaming semi-fluid condition filling the entire retort and 

 forcing itself through the delivery tube. In the case of sand (from 

 the shore of Lake Miclygan) heat was applied for twenty minutes with 

 ;i very small amount of oxygen given off. In every case with manganese 

 dioxide the gas had been entirely driven off in a shorter time with 

 a flame greatly reduced from the normal. In fact a considerable amount 

 of gas bubbled through the meter owing to the rapid rate of generation. 

 With Venetian red a very small amount of oxygen was obtained, al- 

 though the temperature was raised to the point where the entire mass 

 was fused. Subsequent experiments performed in a test tube showed 

 the temperature of fusion to exceed 360° C, while the temperature 

 at which oxygen is liberated from the manganese dioxide mixture as 

 shown by Mahin [Proc. lud. Acad. Sci., P. 170, 1002] does not exceed 

 180° C. Calorimetric computations and direct observation in test tubes 

 show the temperature of the gas to be from 65° to 100° C. It would 

 seem that there is a lowering of temperature at liberation analagous 



