43 



sphere on the exit side there was a cooling effect of 0'2 Cent. The 

 steam, therefore, issued at a temperature above 100 Cent., and, 

 consequently, dry ; showing the correctness of the view which we 

 brought forward some years ago * as to the non-scalding property of 

 steam issuing from a high pressure boiler. 



II. " On the Bromide of Titanium." By F. B. DUPPA, Esq. 

 Communicated by A. W. HOFMANN, Ph.D., F.R.S. &c. 

 Received February 14, 1856. 



A comparison of the boiling-points of corresponding chlorine and 

 bromine compounds, led Prof. Kopp to the interesting discovery, that 

 on the average their boiling-points rise 32 C for every equivalent of 

 bromine which is substituted for an equivalent of chlorine. 



Boiling- 

 point. Difference. 



Chloride of ethyl, C 4 H 5 Cl . . . . 1 1 C. 1 

 Bromide of ethyl, C 4 H 6 Br .... 41 C. / 



Dichlorinetted ethylene, C 4 H 4 C1 2 6 7 C . "1 _ 



Dibrominetted ethylene, C 4 H 4 Br 2 1 33'6C. / 



Terchloride of phosphorus, PC1 3 . 78 C. "I _ 



Terbromide of phosphorus, P Br 3 . 1 75 C. J ' 



If this difference be constant for all chlorine and bromine com- 

 pounds, it becomes obvious that very important inferences in respect 

 to the atomic constitution of these substances may be derived from 

 the determination of their boiling-points. This result has, in fact, 

 been happily applied by Prof. Kopp, as a criterion to determine the 

 equivalent of silicium, a matter of such uncertainty as to have led to 

 the admission of not less than three formulae for silica 

 SiO 



From the difference between the boiling-points of chloride (59 C.) 



* See letter from Mr. Thomson to Mr. Joule, published in the Philosophical 

 Magazine, Nov. 1850. 



