Abstract: A process of and apparatus for colorimetry, whereby an indicator is added cyclically to a fluid stream to indicate the presence or absence of a condition in the stream. The presence of the condition may be indicated by the formation of a precipitate, a change of color, etc. A light source and photocell are located downstream of the point of addition of the indicator and by the difference in an optical characteristic such as the transmissivity or scattering of the fluid, at one or more wavelengths, due to the introduction of the indicator, a measure is obtained of the degree to which the tested-for condition is present in the fluid.

Abstract: An oil slick sampling apparatus and method wherein a substantially annular hoop-like frame adapted to float on water and surround the slick, has an inner annular surface coacted with a surface active material which functions by spreading to compress the area of the oil slick. According to one embodiment the frame is hollow and has one or more openings to collect the oil slick as it is compressed by the inwardly spreading area of the surface active coating; according to a second embodiment the frame is impervious and the slick is compressed by the surface active material inwardly toward a central area thereof whereat suitable collecting means is located to collect the oil slick for further analysis.

Abstract: A method for analyzing sea water, raw water supplies, domestic sewage or industrial wastes for the presence of ionic surfactants, such as detergents, and the determination of whether surfactant is anionic or cationic. The method employs the back titration of a sample to which an excess of cationic surfactant has been added.

Abstract: A control for a polyphase a.c. motor having field coils, each of which is connected to first rectifiers connected to form a first junction and second rectifiers connected to form a second junction and a transistor controlling the current between the first and second junction in response to a control signal.

Abstract: A spatter guard combined with a portable electric food mixer having a thin disc resting on the rim of a beater bowl, the undersurface of which contains a radial sieve extending from the center to the periphery thereof being sized to permit liquid to pass therethrough but to prevent solids from passing therethrough. The disc has a pair of openings for the reception of beater shafts each of which comprise a pair of opposed circular edges connected by linear edges to provide clearance for the beater shafts of the mixer.

Abstract: The retrodirective array antenna of the present invention employs a circular, focusing parallel plate lens to interconnect array elements, thus producing a body with an inherently large radar cross section. By modulating the radiated signal from such an array, it is possible to meet the requirements for passive beacon and data transmission applications. Information transmittal is accomplished via the selection of the modulation function.

Abstract: A rotary compressor having a pair of rotatable impellers in mating engagement in working chambers, each impeller having a plurality of constant cross-sectional profiles, each profile having a plurality of lobes and wells, the trailing well region of each profile communicating with the leading well region of an adjacent profile, an inlet communicating with the working chambers and an outlet located out of the plane of at least one of the profiles on each impeller.

Abstract: A nonpredictable, nondeterministic actuator for switches or the like having two unsynchronized pulse generators delivering pulses to an AND gate which passes an actuating signal only when the pulses from the generators are coincidental. One generator produces a pulse train at a frequency much higher than the other generator which produces very short pulses and has a maximum timing uncertainty or jitter which is greater than the period of the first mentioned generator.

Abstract: A low drag impeller wheel mounted in an enclosure which when installed in the hull of a ship will rotate through the force of water acting upon it, and operate magnetically a pulse generating mechanism that through a current responsive instrument will indicate the speed of the vessel.

Abstract: Embrittlement machining apparatus having an electrolytic container, an anode, a workpiece immersed in the electrolyte forming a cathode, a cutting head adjacent the workpiece and a conduit for supplying an embrittlement agent adjacent the workpiece and adjacent the cutting head.