928 
teen schools have a full four-year high-school 
course in agriculture and will therefore re- 
ceive $500 each in accordance with Article 22, 
Education Law of 1910. In addition to these 
special vocational courses in established high 
schools twenty-three high schools give some 
instruction in agriculture. 
L. S. Hawkins 
CorTLAND, N. Y. 
SCIENTIFIC BOOKS 
The Absorption Spectra of Solutions of Com- 
paratively Rare Salts Including those of 
Gadolinium, Dysprosium and Samarium, 
the Spectrophotography of Certain Chemical 
Reactions and the Effect of High Tempera- 
ture on the Absorption Spectra of Non- 
aqueous Solutions. By Harry OC. JoNEs 
and W. W. Strone. Publication No. 160 of 
the Carnegie Institution of Washington. 
In this monograph the authors present the 
results of their recent spectrochemical investi- 
gations carried out along the three following 
distinct lines: (1) The mapping of the ab- 
sorption spectra of certain comparatively rare 
substances, (2) the spectrophotography of 
some oxidation reactions, and (8) the effect of 
relatively high temperatures on the absorp- 
tion spectra of alcoholic solutions. 
In an introductory chapter a brief review 
is given of some important spectrochemical 
investigations of the last decade concerning 
the nature of the emission and absorption 
centers of light; the connection between these 
centers and molecular and atomic structures; 
the effect of ionization and recombination on 
these centers, and the effects that can be pro- 
duced by physical and chemical agents upon 
the constitution of the emission and absorp- 
tion centers. 
The general method of experiment was 
similar to that employed by Jones and his co- 
workers in their previous investigations. For 
experiments at high temperatures a new form 
of absorption cell was devised, for a descrip- 
tion of which the original monograph. must 
be consulted. Through the kindness of Pro- 
fessor Urbain sufficient quantities of the 
oxides of samarium, dysprosium and gado- 
SCIENCE 
[N.S. Vou, XXXV. No. 911 
linium were loaned the authors to enable 
them to prepare the various salts whose solu- 
tions they wished to study. 
An examination of the spectrograms in this 
and the preceding monographs shows that in 
general the absorption spectra of various salts 
of the same element are very similar. With 
high dispersion the minute structure of the 
bands and groups of bands is shown to be very 
different for different salts of the same ele- 
ment, this being especially true of the salts of 
neodymium. LBeers’s law has been shown to 
hold approximately for nearly all solutions of 
a single neutral salt in a single solvent. Each 
solvent is characterized by a definite absorp- 
tion spectrum, and when a salt is dissolved in a 
mixture of varying proportions of two solvents 
only two definite absorption spectra appear, a 
result which the authors interpret as an indi- 
cation of the formation of definite compounds 
of solvent and solute or “ solvates.” 
In their study of oxidation phenomena 
uranous salts were subjected to the action of 
both weak and strong oxidizing agents, the 
salts being dissolved in single and mixed sol- 
vents. On dissolving uranous chloride in a 
mixture of alcohol and water, the bands 
characteristic of both solvents appear simul- 
taneously. A mild oxidizing agent was 
found to oxidize the “hydrated” salts and 
leave the “alcoholated” salts unchanged, 
while with a strong oxidizing agent both 
“hydrated ” and “ aleoholated ” salts were oxi- 
dized to the uranyl condition. 
Rise of temperature has been shown to 
cause a widening of the bands in solutions of 
a pure salt in a single solvent, the edges of the 
bands becoming hazy. When several salts are 
dissolved in the same solvent the bands be- 
come weaker as the temperature rises. In 
general the center of intensity of the single 
bands remains unaltered with rise in tempera- 
ture. 
This recent publication of Jones and his 
associates is another valuable contribution to 
the literature of spectrochemistry and will un- 
doubtedly find a place on the book-shelves of 
those engaged in spectroscopic investigations. 
No little credit is due the printer for the ex- 
