CHLOROFORM AND CARBON TETRACHLORIDE 



3 1 



two liquids. The last column, precisely similar to the corresponding 

 column in the preceding data concerning bromine, gives the total 

 change of volume in milliliters of 100 milliliters of liquid, caused by 

 the application of each pressure, minus the total change in volume of 

 the same volume of mercury caused by the same pressure. The cor- 

 responding curves are plotted in the diagram Fig. 5. From the aver- 

 age of several large plottings of this kind on two varieties of coordinate 

 paper, the values of the compressibilities of the two liquids contained 

 in the following table were obtained. 



Compressibilities of Chloroform and Carbon Tetrachloride. 



As before, the curve below 100 atmospheres is partly extrapolated, 

 hence the first figure is uncertain in each case. The values are very 

 consistent and are not far different, for the two liquids, each being 

 about one and a half times as compressible as bromine. It is remark- 

 able and an interesting fact that although the carbon tetrachloride is at 

 first slightly less compressible than chloroform, above 200 atmos- 

 pheres, the relative magnitudes are reversed, since the compressibility 

 of the former substance diminishes less rapidly than that of chloroform 

 with increasing pressure. This point will be referred to again. 



It is worthy of note that Grassi found the compressibility of chloro- 

 form to increase with increasing pressure below 10 atmospheres. 

 Whether this is an inaccurate observation, or whether an anomalous 

 behavior really occurs at low pressures, it is impossible to ascertain 

 without further data. It is our intention to pursue the question. 

 Since Grassi's values were obtained at 12 they are not directly com- 

 parable with ours. In any case, the present observations establish 

 beyond doubt the fact that at high pressures chloroform decreases in 

 compressibility with increasing pressure in the usual way. 



From the great compressibility of these liquids, consisting chiefly of 

 chlorine, and possessing boiling points not far from bromine, it seems 

 certain that chlorine must be much more compressible than bromine 

 under similar circumstances. In order to obtain further light upon 

 this important question, which cannot be easily answered by direct ex- 



