SEPTEMBER 38, 1897. ] 
tinually increased. Finally quartz appears 
like an insulator in the same role as water 
in ordinary aqueous solutions. In all these 
cases I wish to keep in mind the results of 
Alexeéff and their recent repetition for me- 
tallic alloys, together with the interpreta- 
tion of these results due to Masson. Ina 
crust subject to variable magnetism, trav- 
ersed by earth currents, sustained by semi- 
metallic carbides of the Mendeleeff-Moissan 
type, containing piezo-electric and thermo- 
electric sources, who can say that electric 
fields are absent? Again, the character of 
the changes contemplated in Gibbs’ famous 
‘phase rule,’ as interpreted by Le Chatelier, 
would here be ionic rather than molecular. 
A question of somewhat allied interest in 
the action of hot water under pressure on 
rock-forming silicates. Investigations of 
this kind have been described in the well- 
known and fascinating book of Daubrée. 
Daubrée’s work, however, is qualitative in 
character, like that of many others in the 
same line, and the furtherance of the subject 
is to be looked for in the quantitative direc- 
tion. Some time ago Becker suggested ex- 
periments on a huge mass of granulated rock 
under the action of steam at exceptionally 
constant temperature. But no thermal 
effect of the action of water could be de- 
tected. ‘True, the boiling point of water is 
a temperature comparatively low for the 
purpose; yet similar experiments made 
with liquid water at over 200° under pres- 
sure were equally negative as to results. 
Experiments of this kind are not very con- 
elusive. The insufficient sensitiveness of 
the measuring apparatus, the rate at which 
heat is carried off compared with the rate 
of generation and other obscure causes mar 
the results. The question may, however, 
be approached in a somewhat different way : 
If water is heated under pressure in glass 
tubes, the volume of water contained de- 
creases as the square, whereas the chem- 
ically active area, 2. e., the inside surface of 
SCIENCE. 
349 
the tube, decreases as the first power of the 
diameter. Hence, in proportion as the tube 
is more capillary, the action of water on 
the glass will produce accentuated volume 
effects. Thus it was shown that the be- 
havior of hot water is profoundly modified 
by its continued action on glass, inasmuch 
as its compressibility increases at a very 
rapid rate with the time of action even at 
180°, until, with the approach of solidifica- 
tion, the observed compressibility is fully 
three times its isothermal value at the in- 
ception of the experiment. Even more 
striking is the simultaneous and continual 
decrease of the length of the column of 
water. Clearly, therefore, the confined 
volumes of glass and included water must 
undergo contraction at 180° in forming an 
eventually solid aqueous silicate, while in- 
creasing compressibility is due to the in- 
creasing quantity of silicate dissolved. 
Now, in nearly all cases the effect of solu- 
tion is a decrease of compressibility. Hence 
the increased compressibility observed is to 
be referred to a precipitation of the dis- 
solved silicate, in response to the action of 
pressure, a result borne out by the appear- 
ance of the tube and by varied correlative 
experiments. It is, however, the volume 
contraction which is particularly interest- 
ing, because of its far-reaching geological 
application. In the first place the measure- 
ments show that about .025 cubic em. of 
liquid water is absorbed per square centi- 
meter of glass surface at 180° C. per hour.* 
The effect of this absorption is a contraction 
of bulk amounting to 18% per hour. So 
large and rapid a contraction is presumably 
accompanied by the evolution of heat. 
Hence, under conditions given within the 
first five miles of the earth’s crust, i. ¢., if 
water at a temperature above 200° and un- 
der sufficient pressure to keep it liquid be 
so circumstanced that the heat produced 
* This is an initial rate of about 180 kilograms per 
square meter per year. 
