E. 8. Holden— Components of Binary Stars. 467 
ored reddish-yellow and the chemical action began. When it 
had apparently ceased, the contents of the flask were shaken 
together, and the solution became at once as colorless as water. 
But on standing in the air the color rapidly returned, spread- 
ing from the surface of the liquid downward. ese phenom- 
ena were repeated again and again during four or five months, 
until the whole of the metal dissolved. According to the reac- 
tion usually assumed to take place under these circumstances, 
5 grams of metal would have required 50 cubic centimeters of 
acid, so that the effect was obtained with only one-fiftieth of 
the amount required by this theory. 
Art. LXIITL—WNote on a Relation between the Colors and Magni- 
tudes of the Components of Binary Stars; by Epwarp S. 
HOLDEN. 
Mucu has been written on the colors of stars, but I do not 
know that a relation. has been found betweeh the magnitudes 
and the colors of binary stars such as is shown by the following 
tables. : 
In 1877 I noticed that, in a general way, the difference of 
the magnitudes of the two components A an of a double 
star was less, the nearer A and B were of the same color to the 
eye. If this was not the result of chance but the consequence 
kindly drawn up. See Tables I and I. ‘ 
able I contains 122 stars certainly biary and with com- 
ponent stars of like color. e magnitudes and colors are 
from the best authorities. The mean difference of magnitudes 
er in magnitude on the average 2°-4. What the physical 
explanation of this curious relation may be, we have not now 
