Haughton — Notes on Neivtonian Chemistry. 
641 
7. Hydriodic Acid (HI). — Iodine and hydriodic acid have the same 
molecular volume as all the preceding compounds. 
2 X 127 
Mol. Vol. Iodine = — ^— = 29-98. 
•765 
Equations (4)' and (5)' become, when /3 = 127. 
128(o'= 127 (1 + 127(o0. 
l-M27.,^-i||o>'--^. 
127 
Equation (6)' becomes 
?^Ml6001(o'2^-254(o'-16129| - 
E X 2048383 
128 
(4) ' 
(5) ' 
(6y 
Fig. 5. 
The change in sign of the absolute term changes the form of the 
curve, which now becomes fig. 5. 
The branch of the curve lying between the asymptotes AE and CD 
lies altogether on the negative side of n^, and is therefore to be re- 
jected; and the quadratic function of w'must be positive, so as to 
give a positive value for n^, and the two branches of the curve with 
which we are concerned lie altogether outside the asymptotes AB 
and CD. 
1 When 1 gram of hydrogen combines with 127 grams of iodine, assumed to be 
gaseous, the thermal effect is very sHght, some heat being gained during the 
operation ; hence the negative sign. The quantity E is much less than 1540. 
