176 Proceedings of the Royal Society of Edinburgh. [Sess. 
their sparing solubility and well-defined crystalline character, the emetics 
were easily obtained in a very pure state. 
The solutions were always tested polarimetrically, and in every case 
the rotations of the equivalent dextro- and Zaevo-solutions were found to be 
the same in amount ; the racemic solutions were tested and were inactive. 
As all that was wanted was a comparison of the effect produced by cane 
sugar on equivalent solutions of the d- and ^-stereoisomers, the method 
adopted was as follows : — Equivalent solutions of the three, d-, 1-, and r-, 
substances were made ; their density, viscosity, and electric conductivity 
were determined at 15° C. and 25° C. A definite weight (1 gram) of cane 
sugar was then added to a definite volume (35 c.c.) of each solution, and 
the density, viscosity, and electric conductivity of the resulting solutions 
again determined. 
The results are given in full in the following tables. As already 
explained, it is the relative viscosity (t]/r] 0 ) which is actually determined; 
the values of rj are obtained from this ratio by multiplying it by rj 0 , the 
viscosity of water at that temperature expressed in absolute units. The 
values of rj 0 are taken from Thorpe and Rodger’s table,* and are as follows, 
rj 0 at 15° C. = 0-011335, and at 25° C. 0-00891. 
The electric conductivities are expressed in Kohlrausch units. 
Owing to their small solubility, the tartar emetics could not be investi- 
gated at a higher concentration than that given in the table, and nothing, 
apparently, was to be gained by working with more dilute solutions. 
Viscosity. 
Table I. — Potassium Tartrates and Cane Sugar. 
Temp. 15° C. 
Mols. per 
litre. 
Optical 
Activity. 
Solution alone. 
Solution + Sugar. 
Difference 
in 7]. 
v/v> 
V 
vivo 
n 
•5 
d 
1T890 
•013477 
1-2935 
•014661 
•001184 
l 
1 T886 
013473 
1-2916 
•014640 
•001167 
r 
1T870 
•013455 
1-2902 
•014624 
•001169 
•25 
d 
1-0870 
•012321 
1T740 
•013307 
•000986 
l 
1*0865 
•012316 
1T732 
•013298 
•000982 
r 
1-0865 
•012304 
1T730 
•013296 
•000992 
•125 
d 
1-0410 
•011800 
1T255 
•012758 
•000958 
l 
10405 
•011794 
1T245 
•012746 
•000952 
r 
1-0402 
•011792 
1T245 
•012746 
•000954 
* Phil. Trans., 185, p. 449, 1894. 
