4 
ASTRONOMY: C. G. ABBOT 
Proc. N. a. S. 
position such as the present-day vit amine preparations. For these reasons 
work on the chemical composition of vitamines is urgently needed as the 
previous attempts along these lines have been more or less unsuccessful. 
This paper deals principally with the antineuritic vitamine. 
As it has been found that brewer's yeast is very rich in antineuritic 
vitamine, this material was selected for this investigation. At first 
autolyzed yeast was used, but on account of its complex composition it 
was later on substituted by dried yeast. The general conclusions derived 
from this work are as follows : 
Autolyzed yeast filtrate, on account of its complexity, represents an 
unsatisfactory material for the chemical isolation of the antineuritic vit- 
amine. Mastic emulsion, Lloyd's reagent (fullers' earth), ferric phos- 
phate, etc., are unsatisfactory adsorbing reagents in that they lack speci- 
ficity. These reagents remove, also, inactive basic materials which cannot 
be separated by our present methods from the active material. Olive 
oil and oleic acid will remove the antineuritic substance from autolyzed 
yeast filtrate, thus showing that it is fat-soluble as well as water-soluble 
in the form of a crude extract. Stachhydrine, trigonelline and allied be- 
taines show no antineuritic activity. Histidine and its esters are likewise 
inactive. 
The active material is readily extracted from dried yeast by means of 
acid methyl alcohol. The extract can be purified by use of the Funk 
silver method and the mercuric sulphate procedure, yielding an apparently 
crystalline active substance. This substance becomes inactive upon dry- 
ing and it is believed that impurities still remain which can be removed 
with additional modifications of the method described in this paper 
(see, /. Biol. Chem.). The present method eliminates purines, histidine, 
proteins and albumoses, leaving a liquid that can be crystallized and prob- 
ably contains histamine or histamine-like substances. The physiological 
action of the active fractions resembles that of extracts from the mucosa 
of the small intestine, when the intestinal and yeast extract are purified 
in the same manner. 
A NEW METHOD OF DETERMINING THE SOLAR CONSTANT 
OF RADIATION 
By C. G. Abbot 
Smithsonian Astrophysicai. Observatory 
Read before the Academy, November 10, 1919 
The Smithsonian Astrophysical Observatory has been engaged for more 
than ten years in measuring the intensity of the solar radiation at the 
earth's surface under such conditions that the intensity as it would be 
outside the atmosphere may be computed from the observations. The 
