Intelligence and Miscellaneous Articles. 233 



2*6. The fusing-point was found, 39°. The boUing-point was 

 exammed by Mr. Duppa with a considerable quantity of substance, 

 the purity of which had been ascertained by analysis. It was 

 observed to be 230° C. The boiling-point of the chloride of tita- 

 nium, as observed by Dumas, and confirmed by Mr. Duppa, is 135°. 

 The difference, 230— 135 = 95 = 3 x 31^, is exactly the same as that 

 observed between the boiling-points of chloride and bromide of silicium. 



This observation furnishes an additional support to the analogy 

 of silicium and titanium, while it points unequivocally to the formulae 



TiCl.3 and TiBrg, 

 as representing the atomic constitution of these two compounds. 



Titanic acid, hitherto universally represented as a binoxide TiOg, 

 would then assume the formula 



Ti03 

 in perfect analogy with that of silicic acid. 



The equivalent of titanium would then be changed from 24*29, 

 the number at present adopted, to 36*39. The protoxide of tita- 

 nium would in this case become a sesquioxide, and the compound 

 hitherto viewed as sesquioxide would have to be considered as an in- 

 termediate oxide — as a combination of the sesquioxide with the ter- 

 oxide, in fact, as a bititanate of sesquioxide of titanium. 



Formulce of the Titanium Compounds, 



It is scarcely necessary to observe, that an alteration of the equiva- 

 lent of titanium on the ground of the difference of the two boiling- 

 points, would be hazardous, if not supported by additional experi- 

 mental evidence, and that further researches on the series of titanium 

 are required in order to establish whether the proposed alteration 

 actually affords a simpler expression for the combining relations of 

 this remarkable element*. 



XXXII. Intelligence and Miscellaneous Articles. 



ABSORPTION OF HEAT BY DECOMPOSITION. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, Parsonstown, August 1856. 



TN reference to Mr. Joule's continued wish to be thought the ori- 

 -*- glnator of the discovery that chemical decomposition absorbs 

 heat, allow me to say that I am sorry to prolong a discussion which 

 involves chiefly personal interests. I would not again urge my claim 



* Some observations on this paper bv Dr. Kopp will be found at 

 p. 190.— Eds. '^ • *' ' 



