The Journal of Physical Chemistry, Volume 4

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Cornell University, 1900 - Chemistry
 

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Page 521 - active on selenium is just outside the red rays, at a place nearly coincident with the locus of the maximum of the heat rays. He showed further that the effect of light, on exposure, is instantaneous, but that on cutting off the light, the return to the normal resistance is not so rapid.
Page 237 - established the important fact that the direction of movement of the particles, as compared with the direction of the current, depends upon their chemical nature. I have shown that the heat-modified proteid is remarkable in that its direction of movement is determined by the reaction, acid or alkaline, of the fluid in which it is suspended.
Page 227 - In the majority of cases where a mineral substance evolves gas under the influence of heat, the gas is the product of the decomposition or interaction of its non-gaseous constituents at the moment of the experiment. The results of such experiments cannot, therefore, serve as basis for speculation as to origin and history of the substances in question.
Page 263 - of dry gelatine are dissolved in 100 cc of a mixture of equal volumes of absolute alcohol and water, a system is produced which is clear and homogeneous at temperatures above 20 0 . As the temperature falls below this limit a clouding occurs, which I find to be due to the appearance of fluid droplets which gradually increase in size until they measure
Page 215 - by mathematical analysis. To attempt, therefore, to teach sound physics and good scientific method without laboratory work on the part of the student is to attempt the impossible. Accordingly the present volume is intended only for use in connection with a course of laboratory instruction.
Page 531 - between the brass and the selenium has contributed to the low resistance of our cells by forming an intimate bond of union between the selenium and the brass." There is but little of theoretical interest in the paper, except that Bell finds the long heating and slow cooling formerly recommended in the preparation of selenium cells, to be unnecessary ; this is probably because selenium
Page 242 - the potential gradient. The coagulating ion is always of the opposite electrical sign to the particle. The salts employed to determine this point were the sulphates of aluminium, copper, magnesium, potassium, and sodium;
Page 263 - On cooling further these fluid droplets become solid, and they begin to adhere to one another. In this way a framework is built up, composed of spherical masses hanging together in linear rows
Page 257 - which govern ordinary chemical equilibrium. In the case of the action of salts on these hydrosols, the relation is not so simple. K does not vary directly with a(u + v), but contains a factor which is approximately squared or cubed by a change from a mono-valent to di- or tri-valent ions. The relation can therefore be best expressed as K
Page 522 - for some time. They showed, moreover, that, on the whole, there is a general diminution of resistance in the selenium as the battery power is increased. Their results indicate that the

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