II RO MO FORM 



33 



periment, we thought it worth while to determine the compressibility 

 of bromoform, because of its close analogy to chloroform. 



Bromoform. 



Merck's "chemically pure " bromoform boiling between 150. 3 and 

 1 50.5 ' was used. Perkin 2 found the specific gravity of this substance 

 to be 2.903 at i5/i5, and 2.SS3 at 25/25. These values reduce 

 to 2.900 at i5/4 and 2.875 at 25/4, from which by interpolation 

 we obtain the value 2.888 at 20/4. 



The determination of the compressibility of bromoform was made 

 in the special jacket (No. IV) devised for the determination of the 

 compressibilities of liquids which do not attack mercury. It was 

 found during the course of the experiment that a slight action between 

 mercury and bromoform had nevertheless taken place ; yet the results 

 can hardly have been vitiated to an extent exceeding one per cent., 

 and for the purpose of this part of the work, namely, the fixing of the 

 position of the compressibility of chlorine with relation to those of the 

 other halogens this degree of accuracy is all that is needed. The 

 method of experimentation is evident from the following sketch'and 

 descriptions. 



The jacket full of mercury weighed 291.6 grams, while the weight 

 of the bromoform, partly replacing the mercury, was 54.63 grams. 



From these data, plotted, the compressibility results for bromoform 

 are readily found to be the following : 



Compressibility of Bromoform. 



Thus the compressibility of bromoform is somewhat less than that 

 of bromine, being about thirteen times as great as that of mercury. 

 Bromoform is only about half as compressible as chloroform. 



1 Corrected tor exposed column, under 760 mm. pressure. 



2 Journal Prakt. Chem. (2). 32, 523 (1885). 



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