CHLOROFORM AND CARBON TETRACHLORIDE 



2 9 



This represents the quantity of iodine, the compression of which 

 was measured. Its volume is 0.943 milliliters, or 0.348 of the volume 

 of its bulb. 



Now x = mc\a = 0.684 m - F rom the values of m given under the 

 work on bulb A the values of .r were calculated and plotted as ordi- 

 nates with the corresponding pressure-differences as abscissas. This 

 was called the curve of x. Then the values found in the work 

 on bulb B were also plotted, using values n as ordinates and pressure- 

 differences as abscissae. The curves were both extrapolated in order 

 to pass through the origin. In order to economize space, the curves 

 themselves are not given here, but in the table below are given all the 

 data needed to reproduce them, {n x) /0.34s/' is the compressi- 

 bility of the iodine. 



Compressibility of Iodine. 



Thus the compressibility of iodine is far less than that of bromine, 

 being only three times that of mercury. This result does not pre- 

 tend to any considerable degree of accuracy ; the small amount of ma- 

 terial used and the complication of the method preventing great pre- 

 cision. It is, nevertheless, sufficiently certain for the present purpose, 

 and accordingly further work upon iodine was postponed. 



Chloroform and Carbon Tetrachloride. 



These substances were next studied, with the justifiable hope that 

 their behavior might furnish some clue as to the compressibility of 

 chlorine. In order to purify the former material, commercial chloro- 

 form was shaken repeatedly with strong sulphuric acid and then with 

 successive portions of water. It was afterwards dried with calcium 

 chloride and twice distilled. During the second distillation two thirds 

 of the product passed over between 61. 2 and 61. 3 C., 1 and from this 

 fraction the material for the compression experiments was taken. 



As before, accurate knowledge of the density is needed. Thorpe 2 

 found for the specific gravity of chloroform the value 1.5264 at o/4 ; 

 and, under the same conditions of temperature, Pierre 3 found 1.5252. 



1 The barometric pressure was 759 mm. and the thermometer reading was cor- 

 rected for the temperature of the projecting column of the thermometer. 

 2 Journ. Chem. Soc, 37, 196 (1SS0). 

 3 Compt. Rend., 27, 213 (1848). 



