IOWA ACADEMY OF SCIENCES. 
99 
REFRACTIVE POWER. 
Pulfrich’s '' Bef Tactometer fur Chemiker^^ was used for the 
determination of the refractive index for the complete series of 
solutions. Three or four observations, at least, were made upon 
each solution; and the mean used in the calculation of the refrac- 
tive power, N = for sodium light. An inspection of the 
tabulated results (see Table I) shows that the most highly con- 
centrated solutions have a lower refractive power than that of 
the solvent, which, however, increases with the dilution until 
at V = 64 a maximum is reached. 
In the last column of the table will be found values for the 
refractive equivalent of the dissolved lithium chloride calcula- 
ted by Landolt’s formula for mixtures, 
p N = Pj Nj + P 2 Ng, in which 
p = weight of the solution. 
N = its refractive power. 
Pi = weight of the solvent. 
Ni = its refractive power. 
P 2 = weight of the lithium chloride. 
Ng = its refractive power. 
Further, for the refractive equivalent, we assume 
Rd = 42.38 N^. 
The value of Rd as deduced from the more concentrated solu- 
tions is 14.9. Gladstone found (J. B., 1869, 173) for the refrac- 
tive equivalent of Cl, 10.7; for the Li, 3.8; which gives 14.5 for 
the salt — a fair agreement. The values of R© derived from the 
high dilutions are materially affected, of necessity, by accumu- 
lated experimental errors, but the latter cannot wholly account 
for the great increase which the table exhibits. 
