It is extremely desirable in the interpretation of resistivity measurements made on porous media containing saline water and hydrocarbons to have at hand a better knowledge of the geometry of the conducting salt water. One geometric characteristic is the tortuosity of the aqueous phase. A method was devised several years ago for the measurement of the tortuosity of completely brine‐saturated sands by the measurement of transit time of ions migrating through the aqueous phase under a potential gradient. This method has been improved and extended to the investigation of the tortuosity of sands containing both brine and oil. Results obtained to date on a group of sandstone samples containing water and oil indicate that there is a relation between the tortuosity of the aqueous phase, the brine content of the sand, the resistivity of the brine, and the resistivity of the gross sample. These results were used to relate the saturation exponent, n, which is customarily used in the interpretation of the electric log, to the tortuosity and apparent cross‐sectional area of the electrolyte through which electric current flows.

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Marine corrosion is of considerable interest from the technical standpoint in so far as it involves most of the known classical situations of the electro‐chemical theory of corrosion, and is primarily concerned with a metal immersed in an electrolyte. In the case of ships, the area of immersed steel can well vary between 2,000 and 15,000 sq. yds. but, of course, the supply of electrolyte is unlimited.

NECESSITY FOR A SMALL CUPOLA.I . At the Puget Sound Navy Yard it wm found that the considerable variation in the volritne of foundry work interfered greatly with the economical operation of the cupola furnaces. Thereare three cupolas in the foundry, the smallest of which is lined to a4 inside diameter, and the one best suited i n size to the melt for the day is used. In slack times, however, the smallest of the three cupolas is much too latge to melt a day's work economically. It was very f r q w n t l y the case that three M four days would elapse before there would be a sufficient number of molds ready to permit an economical melt of iron.2. The resalt of this condition was, in slack times, that we were condtantly choosing between two evils : either the jobs requiring iron castings were delayed for a period of o m to four days in tbe foundry or the foundry was melting iron h i l y in a most extravagant manner. The latter course of action was more frequently decided upon in order toavoid delays in the mochina abop and on the outside. The result was that the cost of melting iron was abnormally but unavoidably high.5 The principal loss o~d by operatilg la cupola at a small percentage of its normal capacity is in the txwzes8ive amount af coke wed. This tosa is largdy dne to the fwt that the first charge of coke, the '' bed," contains about five times as much coke as the other, chaw* and mast be aa large for a small melt of iron as for a large one The qfsola itsdf, which must be heated, will absorb an cxccrrslve amount d heat.

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