The osmotic pressure of aqueous solutions Volume 198; report on investigations made in the Chemical laboratory of the Johns Hopkins university during the years 1899-1913

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1914 Excerpt: ...to 0.001 normal. The effects were seemingly good, in that higher resistances could be obtained at any single "running" than before and the cells appeared to require less soaking between measurements. Still later a 0.01 weight-ion-normal solution of ferrocyanic acid was substituted for the potassium salt in all operations connected with the deposition and reinforcement of membranes. The results of the last substitution are very promising, and the acid seems likely wholly to displace the salt. It has been found that, while potassium salts are in a marked degree injurious to the membranes and may easily ruin them, the salts of lithium are comparatively harmless. This discovery has been utilized to some extent and with advantage in the deposition of membranes by substituting the ferrocyanide of lithium for that of potassium. 4. ACTIVITY OF THE MEMBRANE. In discussing the so-called "thermometer effects," which are due to fluctuations of temperature, the fact was emphasized that the passage of solvent through the membrane is by no means instantaneous, and that it may be exceedingly slow. We have, therefore, a "barometer effect" due to fluctuations of atmospheric pressure. Barometer effects are, however, less troublesome than thermometer effects, because, as a source of error in the measurement of osmotic pressure, their magnitude is limited to the comparatively small variations in atmospheric pressure. Moreover, the errors due to them can be eliminated by correcting the mean of all the daily observations of osmotic pressure by the mean barometric pressure for the whole period within which an experiment is in progress. The activity of a membrane, i. e., the rate at which the solvent will pass through it, depends, of course, in the fir...