408 De. Andrews on the Heat developed during the Formation, Sfc. 



The slight differences between these numbers are fully within the limits of the 

 unavoidable errors of experiment, and leave no doubt of the truth of the prin- 

 ciple just enunciated. 



37. On a future occasion I hope to have an opportunity of describing a more 

 extended series of experiments now in progress, on the heat developed during 

 the combination of other elements with chlorine, bromine, and iodine ; and, till 

 that opportunity occurs, I shall reserve any further observations of a general cha- 

 racter upon the preceding results. Meanwhile they may be thus recapitulated : 



1. The heat developed during the combination of a given quantity of zinc 

 with chlorine gas is sufficient to raise an equal weight of water through 2766°, 

 while that evolved during the combination of the same metal with bromine, in 

 the fluid state, is 2284° ; and with iodine, in the solid state, 1474°. 



2. The heat developed during the combination of iron with chlorine, bro- 

 mine, and iodine (which always takes place under the form FejClg, Fe^Brj, 

 Fcj I3) is sufficient to raise an equal weight of water through 3246°, 2302°, and 

 834° respectively. 



3. When solutions of the sesquichloride, sesquibromide, and sesquiiodide of 

 iron become converted into proto-compounds by combining with iron, the heat 

 evolved in all is the same for the same quantity of iron dissolved. 



