iSyy.) 
Notices of Books. 
123 
the solid portion of the surface tends to increase, we are unable 
to decide. We must remember that the sea is no less replete 
with organic life than the dry land, and if we could contract it 
we should merely give greater scope to certain living forms at 
the expense of others. 
In another chapter we read — “ I hold therefore that the gravi- 
tative force is the finest that exists in all creation, as it consists 
of the ultimate atoms conceivable in space. As this matter has 
no intervals or pores, it can consequently contain no heat-matter. 
But whatever in nature contains no heat must have cold, — con- 
sequently gravitation is absolutely cold.” 
In short, the author — as he states in other passages — regards 
cold not as a mere degree of heat, low with regard to our feelings 
or to the ordinary temperature of objects around us, but as 
something actually existing in nature. This is one of the leading 
dodtrines of Forfar’s “ Trinology.” Nitrogen, the author con- 
siders, if compressed by a sufficient degree of cold, is changed 
into infinitely small particles of iron ! “ From the highest strata 
of the atmosphere in which this took place these particles fell, 
by reason of their gravity, to the lowest, and thus became dif- 
fused over the whole surface of our globe. It is therefore not to 
be wondered at if iron is to be found everywhere.” With this 
sentence we will conclude our notice of this extraordinary work, 
leaving our readers to meditate on this new theory of the origin 
of iron. 
Statistical Investigations on Mental Diseases .* By F. W. 
Hagen. Erlangen : Eduard Besold. 
We have here an application of the statistical method to the 
solution of certain questions connected with the painful subjedt 
of mental alienation. After a very able Introduction, treating of 
medical statistics in general and of the statistics of this class of 
disease in particular, the author gives a short account of the 
asylum for central Franconia. He then discusses the influence 
of the duration of mental disease previous to the admission of a 
patient into the asylum, upon its total duration, the general mor- 
tality of the insane, the various forms of the disease, and the 
influence of sex, age, and civil status, t From these topics he 
passes to the capital point, the heredity of insanity. Here his 
observations lead him to a result which he rightly terms “ con- 
solatory,” namely, that “ the inheritance of psychic disease does 
not occur so frequently and so unconditionally as might be sup- 
* Statistische Untersuchungen liber Geistes krankheiten. 
t The word which we, for want of a better term, translate by “ civil status ” 
does not refer to rank or occupation, but to the distinction between the un- 
married, the married, and the widowed. 
