APRIL 29, 1915] 
NATURE 
2o7 

of the rare elements, and some of the more im- 
portant are given. Zirconium in particular has 
properties that render it valuable in many ways; 
the metal has a very high melting point, and is so 
hard that it can be used as an abrasive and for 
glass-cutting; the oxide is largely used in the 
manufacture of crucibles and furnace linings, and 
for many other purposes; it has even been sug- 
gested as a toilet powder. Among the properties 
of the metals of the cerium group is the power of 
forming pyrophoric alloys; cerium with 20 per 
cent. of iron is said to form an alloy which gives 
showers of sparks when scratched or struck, and 
“lighters ’ made from this and similar alloys are 
already in use. 
The last chapter of the book is devoted to a 
discussion of the technical possibilities of titanium 
and its compounds ; there are many uses suggested 
for this interesting element; its very high melting 
point, 2350° C., renders its employment in metal- 
lurgy difficult unless first alloyed with iron, as 
ferrotitanium; from this many valuable alloys 
have been formed. 
But enough has been said to show that Mr. 
Levy’s book is no ordinary text-book; it is ori- 
ginal in its design, contains a vast amount of 
valuable information connected with the tare 
earths and the minerals in which they are found, 
and gives a very complete account of the pres2nt 
technical application of many of them; and it 
offers great encouragement for further research in 
this interesting and little-worked branch of inor- 
ganic chemistry. James H. GarpINer. 

ABNORMAL PSYCHOLOGY. 
(1) Psychopathology of Everyday Life. By Prof. 
S. Freud. English Translation with Introduc- 
tion by Dr. A. A. Brill. Pp. vii+342. (Lon- 
don: T. Fisher Unwin, 1914.) Price 12s. 6d. 
net. 
(2) The Unconscious. The Fundamentals of 
Human Personality, Normal and Abnormal. 
By Dr. M. Prince. Pp. xiv+549. (New York: 
The Macmillan Co.; London: Macmillan and 
Co., Ltd., 1914.) Price 8s. 6d. net. 
(1) HERE has been a rapid growth of 
interest, during recent years, in the 
theoretical explanation and practical treatment of 
mental diseases, especially of those so-called 
“borderland” cases between the normal and the 
definitely insane. The problems involved have 
aroused vigorous controversy, and the most con- 
flicting views have been put forward by different 
schools of thought. Among the exponents of 
these various doctrines two of the most dis- 
tinguished are Prof. Freud, of Vienna, and Prof. 
Morton Prince, of America. 
NO. 2374, VOL. 95] 


Broadly stated, Freud’s psychological system is 
based upon a fundamental distinction between two 
classes of memories and mental tendencies, viz., 
ordinary memories and tendencies and those that 
have for one reason or another been repressed. 
The latter are those involved in mental conflicts 
and accompanied by pain. They constitute the 
true “unconscious” of the mind. The other 
memories are classed by Freud as “ pre-con- 
scious.”’ Unconscious memories and mental ten- 
dencies retain their original intensity, and although 
outside of consciousness continue to act, and from 
time to time affect consciousness. ‘‘Like the 
shades in the Odyssey,” says Freud, “they come 
to life again as soon as they have drunk blood.” 
When especially intense, or when the repressing 
power of the mind is in one way or another 
diminished, they may produce the symptoms of 
hysteria and of other forms of mental disease. 
But they are also the cause of dreams in normal 
persons, and of the apparently unintentional mis- 
takes in speech, writing, and other actions, to 
which we are all more or less subject when our 
attention is distracted. Freud tries to sustain 
this latter view in his ‘‘ Psychopathology of Every- 
day Life.” He contends that the method of 
psychoanalysis,! or free association, demonstrates 
conclusively that such slips of memory, speech, 
and writing are really intentional, and due to 
the concomitant working of unconscious mental 
tendencies. In his view the problem for psych- 
ology is not why we are able to remember, but 
why we come to forget, and his own solution of 
the problem is that we forget the unpleasant, 
except when special factors make this forgetting 
impossible. 
The thecry is a comprehensive one, and not so 
easy to refute as might at first sight appear. 
There can be no doubt that in quite a number of 
cases repression plays an important part in the 
forgetting of unpleasant incidents, and that un- 
conscious mental tendencies sometimes prove their 
existence by disturbing our speech and other acts. 
But the exceptions are numerous, and even some 
of the cases which Freud himself analyses at 
length seem to admit of other explanations. The 
book is extraordinarily interesting, however, and 
full of hints for the student of human nature. 
(2) Dr. Prince’s book is an excellent intro- 
ductory text-book for medical psychologists. It 
sets out very clearly the various senses in which 
the word “unconscious” has been used by 
different writers, and shows how important the 
concept, when adequately defined, is for abnormal 
psychology. Morton Prince distinguishes what 
he calls the co-conscious from the unconscious. 
1 See ‘! What is Psychoanalysis?” Naturg, February 5, 1914. 
