146 APPENDIX II. 



obvious that chlorate of potash, on being decomposed, 

 furnishes considerably more heat than that which is 

 necessary to gasify the oxygen which it evolves. It 

 was therefore necessary to determine the amount of 

 heat thus evolved by the quantity of chlorate of 

 potash (9'75 grams) mixed with one gram of the 

 substance burnt in each of the following determina- 

 tions. This was effected by the use of two copper 

 tubes, the one placed within the other. The interior 

 tube was charged with a known weight of the same 

 mixture of chlorate of potash and peroxide of manga- 

 nese as that used for the subsequent experiments, 

 whilst the annular space between the two tubes was 

 filled with a combustible mixture of chlorate and sper- 

 maceti, the calorific value of which had been previously 

 ascertained. The latter mixture was ignited in the 

 calorimeter as before, and the heat generated during 

 its combustion effected the complete decomposition 

 of the chlorate in the interior cylinder, as was 

 proved by a subsequent examination of the liquid in 

 the calorimeter, which contained no traces of unde- 

 composed chlorate. The following are the results 

 of five experiments thus made, expressed in units of 

 heat, the unit being equal to 1 gram of water raised 

 through 1 C. of temperature : 



Units of Heat. 



1st experiment 340 



2nd 300 



3rd 375 



4th , 438 



5th 438 



5)1891 

 Mean 378 



