Abstract: A plurality of ultrasonic transducers mounted linearly on a belt that is contained and supported by a housing. The housing has wheels and handles mounted on its sides to allow an operator to grasp the apparatus and roll it across the surface of a test object along a line normal to the belt. The transducers are electrically connected to various devices which enable pulse echo testing to be performed on the test object and make the results immediately available as a picture either on paper or on a video monitor. The belt is moved laterally and cyclically back and forth as the apparatus is rolled longitudinally and the transducers are sequentially excited to emit ultrasonic waves, thus testing a swath having a width equal to the extremes of lateral motion of the line of transducers. A dynamic counterbalance swings 180.degree. out of phase with the cyclic motion of the belt, and serves to damp out the vibration generated by the belt's motion.

Abstract: A multi-transducer ultrasound probe including a housing having an ultrasound window with a torquer driven pulley system for positioning and oscillating a selected one of the multi-transducers in the window while activating the selected transducer.

Abstract: The apparatus consists of at least one test-tube carrier defining seats for test tubes. The carrier is moved by oscillation or rotary motion about a horizontal axis under the influence of time control means. A structure which is vertically movable relative to the test tubes is fitted with individual means for the photometric observation of the data relating to each test tube and is controlled by time-control means. Processing and recording means collect data relating to the presence of each test tube, the presence of a sample, and the level of said sample, for each test tube seat.

Abstract: A method and apparatus for determining the thawing point of jet fuels by first cooling a sample of the fuel until crystals appear and then heating the sample until the crystals disappear, detecting the point at which the crystals appear both thermally and optically, detecting the point at which the crystals disappear both thermally and optically and correlating the resulting measurements to obtain an indication of the thawing point.

Abstract: Coagulation is detected in a fluid sample such as blood which has been inserted into a cartridge and operated on by an actuator mechanism. The cartridge may be of either of two types: a plunger sensor cartridge wherein a plunger assembly is reciprocated in a predetermined manner within the fluid sample and the descent of the plunger assembly is sensed to determine coagulation conditions, and a gas flow cartridge wherein gas is passed through the fluid sample to transmit liquid in bubbles and the accumulation of the coagulating liquid from the bubbles is sensed to detect coagulation. An actuator mechanism operates with either one or both types of cartridges to create the conditions under which coagulation can be detected and to sense the coagulation detection conditions. The actuator mechanism reciprocates the plunger assembly and forces gas through the liquid sample to create the bubbles.

Abstract: Endotoxin contents in samples can be determined qualitatively, or quantitatively, singly or in parallel, with high precision in a short time by a process comprising applying a light to each sample solution, measuring an initial transmitted light amount I.sub.0 and a transmitted light amount at a time t, I(t), to give a ratio R(t)=I(t)/I.sub.0, and judging a gelation point by a threshold value of R(t), or further obtaining a gelation time from the gelation point. An apparatus used therefor is also disclosed.

Abstract: An acoustic imaging system having an array of N transducers arranged for transducing transmit electrical signals into acoustic pulses and for transducing acoustic pulse echos into electrical receive signals has a transducer multiplexer that connects in substantially cyclic order any one of a selected group of M adjacent transducer elements to one of a plurality of substantially identical transmit or receive channels. Each channel includes phase changing means for dynamic focusing, such as a mixer driven by one of a plurality of individually phased clocks. A control demultiplier orders connection of an appropriate one of the differently phased clocks to the mixer of each channel in an order precisely corresponding to the cyclic ordering of the transducer connections by the transducer multiplexer as groups of M adjacent transducer elements are selected to form acoustic scan lines stepped across the entire array.

Abstract: A plurality of ultrasonic transducers or probes are positioned around a region of an object such as a steel tube to be inspected. One of the ultrasonic transducers is energized to emit an ultrasonic beam into the region, and ultrasonic waves reflected from and transmitted through the region in response to the emitted ultrasonic beam are received. Sound pressures are then measured from the reflected and transmitted ultrasonic waves, and an evaluation value is produced by arithmetically dividing the sound pressure of the reflected ultrasonic wave by the sound pressure of the transmitted ultrasonic wave.

Abstract: The gelation testing apparatus includes a closed fluid circuit in which a sample of the substance to be tested is contained. A pressurizing device, such as a pump, is connected into the closed fluid circuit so that the pressure within the closed circuit can be changed. A pressure detecting device, such as a differential pressure transducer, is connected into the closed fluid circuit for detecting a pressure differential across the sample in response to the operation of the pressurizing device. Through the pressurizing device, the system pressure can be subjected to oscillating pressure pulses. The apparatus also can have the ability to control the temperature of the sample. This apparatus is used by placing the sample in the closed fluid circuit, creating a pressure pulse within the closed fluid circuit on one side of the sample, and detecting whether the pressure pulse is transmitted across the sample. This can be performed under controlled pressure and temperature conditions.

Abstract: The invention combines a plurality of ultrasonic ranging transducers (11) arrayed proximate the end (12) of a movable robot arm (13), all transducers (11) being mounted to a common base so as to be pivotally movable both horizontally and vertically relative to the robot arm (13) by stepping motors (17 and 20). By controlling the pivotal movements of the transducer array (10) by a microcomputer (22) so as to look in the direction of intended travel of the robot arm end (13), and as to the robot arm end (13) moves, unexpected objects in the path of the robot (14) or aberrant motion by the robot (14) become easily detected. Upon the sensing of an obstruction to the direction of motion of the robot arm (13), or aberrant motion thereof, a signal from the microcomputer (22) to the robot (14) controls will halt further operation until the obstruction is removed or the problem corrected.

Abstract: An electronic scanning apparatus ultrasonic imaging adapted to converge or deflect an ultrasonic beam by controlling the amplitude and phase of the vibration of each transducer in a transducer array consisting of a plurality of regularly-arranged transducers, and adapted to move the ultrasonic beam by selecting from all of the transducers constituting the transducer array at least one transducer forming a transmitting and receiving aperture.

Abstract: A gas flow cartridge in which to conduct analytical coagulation tests on a sample of fluid such as blood includes a tube-like member and a resilient flexible membrane having a slit formed therethrough to divide the tube-like member into an upper reaction chamber in which the test takes place and into a lower reagent chamber which initially contains reagent to be mixed with the sample of liquid upon which the test is to be conducted. The contents of the reagent chamber are forced through the slit in the resilient flexible membrane due to the flexing of the membrane around the slit when pressure is applied. Once the reagent is in the reaction chamber with the sample of fluid, a flow of gas is forced upward through the slit in the membrane during the analytical test.

Abstract: Method for measuring the coagulation time of a blood sample in which a sample-reagent mixture is formed by introducing the sample and at least one reagent into a cuvette.To reduce the operating and material costs, the sample-reagent mixture is so moved in a stationary cuvette that the mixture flows back and forth around an edge projecting into the cuvette, whereby a clot forms on this edge.

Abstract: A compact, transportable apparatus includes test equipment for operating on a sample of slurry within a single container to determine the compressibility, thickening time, and static gel strength of the sample. The static gel strength test is particularly performed with a load cell vertically moved along a lead screw, which load cell is directly connected to a drive mechanism for driving a paddle at a very slow speed through the sample.

Abstract: A universal tool for the weld inspection of tubular objects such as reactor vessels is disclosed. The tool is constructed from an array of transducers mounted in groups for common inspection of a particular weld volume. The individual transducers, as well as the groups, are arranged in a compact assembly for minimizing the overall dimensions of the tool and its corresponding weight. The transducers are arranged in a manner which permits inspection of tubular objects having different radii of curvature and corresponding different diameters with a single tool without the need of having to individually adjust the orientation angles of the transducers.

Abstract: A method for determining allergenic sensitivity of a mammal is disclosed. The method involves measuring the time required for hemostasis of a blood sample with an allergen in the presence of a blood clotting inhibitor and comparing the time required for hemostasis in the presence of a blood clotting inhibitor and the absence of the allergen. The sensitivity to the allergen is determined by determining the difference in time required for hemostasis.

Abstract: An appartus and method for testing characteristics of a substance, such as a cement slurry to be used within an oil or gas well, are provided. The apparatus includes a single drive motor which can be actuated in either a dynamic mode or a static mode to measure, in the preferred embodiment, either consistency or static gel strength of the substance. A single display is switchably connectible to one of two scaling circuits which scale a single transducer output signal to provide the desired measurement.

Abstract: Method of measuring the time of coagulation of samples of fluid products such as, for example, samples of blood plasma, wherein the dose of liquid substance to be analyzed is introduced into a small cup (1) the base (1a) of which is shaped to serve as a circular rolling path (1b) for a ball (2) disposed in the lower part of the cup which is actuated with a non-rotary circular movement be means of an eccentric (3-3a) causing a rotation of the ball in a circular path in the base of the cup. The gradual slowing and/or halting of the rotary movement of the ball caused by the thickening or coagulation of the sample of the medium or liquid substance contained in the cup, for example following the introduction of a reactant, is ascertainable visually or, preferably, by any suitable automatic detection system.

Abstract: A measurement method for determining the state of coagulation of raw milk in a production process for, for example, cheese or yogurt. According to this method, the state of coagulation of milk can be determined by placing a metal wire in the milk and, while feeding an electric current continuously or intermittently to the metal wire, measuring the temperature of the metal wire over a given period of time.

Abstract: A system for measuring bleeding time in vitro is disclosed in which blood is passed under pressure through a porous element and the resulting volumetric flow is measured. The porous element is provided with a through aperture and supported in such a manner that the blood moves through the aperture and not laterally into the porous element. The porous element can be soaked in a solution, for example, adenosine diphosphate, which coagulates the platelets and in this manner it is possible to reproduce in vivo bleeding conditions.

Abstract: Disclosed is a method for measuring aggregation in sponge cells using a clinical aggregometer. In addition, using the marine sponge cell as an in vitro model for neutrophil aggregation, a method to determine the relative anti-inflammatory properties of non-steroidal anti-inflammatory pharmaceutical agents by clinical aggregometry is also disclosed.

Abstract: A multitransducer ultrasonic probe having transducers of different sizes for the nondestructive testing of mechanical parts. The probe has at least one line of M transmitter and/or receiver ultrasonic transducers, a control unit for the activation of at least one group of m juxtaposed transducers, selected from the M transducers and for the displacement of the activated portion of the probe after each activation. The M transducers all have different sizes and are arranged in monotonic manner in accordance with their sizes, the sizes being determined so as to scan an object to be inspected with a redundancy rate which is independent of the depth of the locus to be inspected.

Abstract: Coagulation is detected in a fluid sample contained in either a gas flow cartridge or a plunger sensor cartridge, either one of which may be inserted in an actuator mechanism which has the capability of acting on either type of cartridge. Coagulation is detected in the gas flow cartridge by optically sensing the accumulation of coagulating liquid in a foam member at the top of the reaction chamber. In the plunger sensor cartridge, a plunger assembly is raised and released to descend through the sample of liquid in the bottom of the reaction chamber. The plunger assembly descends more slowly upon an increase in the viscosity of the fluid sample due to coagulation. Both cartridges include a lower reagent chamber, an upper reaction chamber, and means initially sealing and thereafter communicating the contents from the reagent chamber to the reaction chamber.

Abstract: In order to measure an ex-vivo bleeding time, a blood sample is applied on a measuring opening in a support. A pressure difference is created across the measuring opening and then time is measured during which a definite reduction of size of the measuring opening occurs due to aggregation of blood platelets.

Abstract: An improved clot activator system for reducing the clotting time for blood samples in serum separation tubes, and the like, as well as increasing the degree of clotting, while at the same time, reducing the cost of production. This is achieved by the addition of glass pieces to the tube which pieces are formed in a particular way by a sol-gel process. The particles are pieces of glass, and are a porous substantially rigid amorphous inorganic sponge with substantial reactive surfaces. When a blood sample is introduced into a serum separation tube containing such pieces, the blood enters the interstices of the pieces causing fragmentation thereof, which fragmentation causes sound and shock waves which, in turn, enhance the clotting of the blood.

Abstract: An ultrasonic coagulation monitor for measurement of prothrombin times and related coagulation times includes at least one piezoelectric crystal operated at a fixed frequency near its resonant frequency. A sample of material to be analyzed is placed in acoustic communication with the crystal. The voltage across the crystal is monitored in order to detect a voltage change, preferably a drop, that occurs upon coagulation of the sample. A timer is included that is turned off at a predetermined voltage drop corresponding to a particular stage of coagulation desired to be timed. In an alternative embodiment of the invention a second crystal is included and is mounted a predetermined distance from the first crystal to define a cavity therebetween. One crystal is driven by the frequency oscillator circuit and the material the coagulation of which is to be measured is placed in the cavity. A voltage sensing device senses the voltage across the second crystal and controls a timer as in the first embodiment.

Abstract: An automatic flaw detection apparatus comprises a supporting frame; a hollow shaft which is supported on said frame in a freely rotatable manner through a bearing, and through the interior of which passes a material to be inspected; a holder disposed within said hollow shaft, and extending in the longitudinal direction of the axis of said hollow shaft, and rotating in association with said hollow shaft; sensing means incorporated in said holder to detect any defect in said material to be probed; and a signal transmission device interposed between said hollow shaft and said supporting frame, and to transmit the flaw detection signal from said sensor means to outside.

Abstract: Apparatus and methods for measuring milk coagulation time and rigidity in the manufacture of fermented dairy products such as cheese. The apparatus includes a substantially flat, disc-shaped probe which is suspended from a wire into a fermented dairy product-making vessel filled with milk. The probe is reciprocated through a small vertical distance within the coagulating milk in the vessel, and the increasing resistance to the probe communicated through the wire as the milk coagulates is continuously measured. When the measured probe resistance reaches a predetermined value, it is time to cut the curd formed by the coagulating milk. The present invention provides apparatus which can be used on both an industrial scale and a laboratory scale.

Abstract: For the inspection of a square billet, an ultrasonic testing technique using an angle beam is performed using a phased array system. The phased array probe is disposed in a plane perpendicular to the axial direction of a square billet, at a prescribed distance from the surface of the billet and set at a prescribed angle with respect to the billet surface. The billet is inspected both inside and at the surface layer when the ultrasonic beam is electronically scanned. Inspection of the surface layer only is also performed using a surface defect inspection apparatus. Determination of internal defects (including subsurface defects) is performed based on the subtraction of information from the surface defect inspection from the information from the ultrasonic inspection.

Abstract: A gas flow cartridge includes a tube-like member which defines a reaction chamber in which a pool of liquid is subjected to an analytical test. A coating of debubbling agent is applied to an area of the tube-like member above the reaction chamber. The debubbling agent collapses bubbles of noncoagulated fluid but allows bubbles of coagulated fluid to continue an upward movement above the area where the coating is applied. Coagulation is detected by sensing the coagulated bubbles moving upward in the tube-like member. A quantity of activator agent is initially confined with the reaction chamber, preferably within a structure defined by a segment of paper-like material formed into an activator retaining form. The paper-like material unrolls or unfolds during the analytical test.

Abstract: A gas flow cartridge in which to conduct a coagulation-related test uses an elongated pin member movably positioned within a communication opening which separates a reagent chamber from a reaction chamber. A first portion of the pin member has an operative configuration for sealing the communication opening when the first portion is positioned in the communication opening. A second longitudinally displaced portion of the pin member opens the communication opening to further communication therethrough upon longitudinal movement of the pin member. At the commencement of an analytical test, a plug member is moved upwardly to contact the pin member and move the first portion out of the communication opening and the second portion into the communication opening. The upward movement of the lower plug member forces the contents of the reagent chamber through the opened communication opening and into the reaction chamber.

Abstract: In a method and an apparatus for detecting a sound source, a measurement plane to be observed is automatically scanned in two-dimensional manner by means of two microphones which are spaced apart from each other by a given distance and are moved by a traversing device. Outputs of these microphones are sampled for successive measurement regions and then are processed by processing circuit including a fast Fourier transform to derive acoustic intensities with respect to various frequencies in a given frequency range. Then, a distribution of the acoustic intensities is indicated on a display device by using various indication techniques. Therefore, since the measurement is effected by using the acoustic intensity representing both a sound power and a propagating direction, the analysis of the sound source can be performed in an easy and accurate manner, and an entier apparatus can be small in size and inexpensive in cost.

Abstract: A movably mounted element (1) is stabilized with respect to a desired path according to one component of movement. The element is mounted with complete freedom of movement along that component of movement which takes part in the formation of the actual path and to maintain or return the movable member (1) to the predetermined path, for example, maintaining a spray manifold parallel to the ground. With the aid of a jack (10) there is exerted, between the movable member and its support point or points (3) and as a function of the position of the movable member with respect to the desired path, one or more forces whose magnitude is independent of the position of the movable member with respect to the points of support. The invention is applicable to movable members having plural degrees of movement in rotation and/or translation and particularly for the stabilization of a spray manifold.

Abstract: An apparatus and method for continuously measuring the coagulation, gelation, denaturation or other related phase transition process of food components and related biomaterials utilizing a single sample by sensing the force generated by the sample during the coagulation, gelation, denaturation or other related phase transition process thereof. A force sensing device including a sample engaging probe is provided. As the phase transition of the sample progresses, the increasing solid phase of the gelled matrix surrounds the probe and results in a continuous increase in the pressure exerted by the matrix on the probe. This force is believed to correlate with the strength of the matrix as phase transition progresses. The increased force is then measured and recorded.

Abstract: A method for non-destructive, qualitative testing of properties of materials, whereby ultra-sonic waves are transmitted in the direction of the material. Ultra-sonic waves reflected by the material are received. The orientation of the material relative to the direction in which the ultra-sonic waves are transmitted is changed in a predetermined way, such that the transmitted ultra-sonic waves arrive at the material under varying angles of incidence and from different directions.

Abstract: A transducer assembly is provided which performs simultaneous imaging and flow measurement. Separate imaging and Doppler transducers are mounted on one face of the assembly. Each transducer type is backed by backing material which provides damping in accordance with the performance criteria of the different transducer types. The transducer types may be mechanically focused in the same direction so that flow measurements are made in the center of the area being imaged.

Abstract: The invention provides a photometric method of determining courses of reaction in a specimen, in which method the intensities of the transmitted light and of the stray light are measured, wherein the two intensities are measured simultaneously and the electrical signals corresponding to the transmitted light and to the stray light are combined to form one signal. The invention makes it possible to perform reliable measurement even with low levels of transmitted and stray light.The method is preferably used in determining the coagulation times of blood. Apparatus for carrying out the method is also disclosed.

Abstract: Materials and structural components having irregular shapes may be tested two ultrasonic testing heads which are movable in unison in the direction in which the cross-section of the material or component being tested changes. The synchroneously moving testing heads are spaced from each other in a direction extending across the moving direction. The testing heads are ultrasonic receivers connected with their outputs to a comparing device which provides an error signal when the amplitude ratio of the received signal changes. The amplitude ratio is formed between the amplitudes of the ultrasonic signals received by both testing heads. Preferably, the comparing device comprises an amplifier which amplifies the amplitude of the received second signal by an amplification factor which is proportional to a deviation of the amplitude of the received first signal from a reference value. The error signal is recorded, for example, by a coordinate plotter.

Abstract: A method of sensing the no-flow temperature of a liquid comprising the steps of varying the temperature of the liquid, sensing the temperature of the liquid, supplying pressure pulses to the liquid and sensing the resistance of the liquid to the flow of the pressure pulses as an indication of the ability of the liquid to flow.

Abstract: In an exemplary embodiment, a transducer element row W.sub.1 through W.sub.m has a signal delay device for the delay of arriving echo signals in such a manner that phase balance of the individual signals result at the output. It is the objective of the disclosure to construct such an apparatus with which, given a specified number of transducers, the grating lobes in the directional response of the antenna are eliminated, and nevertheless the electronic outlay can be kept within boundaries. This objective is achieved in that the signals are transmitted, in groups, respectively, by the delay device to individual adders whose output signals are linked in a unit for quasi-multiplicative processing. In the case of digital technique, through binary signal processing, a considerable simplification results accompanied by the elimination of the interfering directional response of the resolution capability.

Abstract: The transmitter comprises an array of electro-acoustic transducers (1), each of which is connected to an oscillator circuit (9) which has a start input (11). The start inputs (11) successively receive start signals from a start signal generator (13) which comprises a number of comparators (15), each of which comprises a first input (17) and a second input (19). The first inputs (17) are together connected to an output of a sawtooth generator (21), the second input (19) of each comparator (15) are connected to a direct voltage source (23). A direct voltage source (23) is provided for each start signal to be successively generated at least some of the direct voltage sources being controllable in common.

Abstract: A rotary ultrasonic scan head includes a housing 10 consisting of generally symmetrical housing portions 10A and 10B having respective mating surfaces 14 and 16 that abut when the housing portions are assembled. A cavity is defined within the housing by recesses 18, 27, 34 and 38 in housing portion 10A and by complementary recesses 20, 28, 36 and 40 in housing portion 10B, by boot 50 disposed on the housing portions in assembly, and by pressure-compensating diaphragm member 42 disposed within the housing portions in assembly. A rotor 12 including a plurality of ultrasonic transducers 22, an impeller 24, and an optically encoded member 26 is supported for rotation within this cavity. An acoustic coupling and driving fluid is supplied to and withdrawn from the cavity through fluid inlet bore 68 and fluid outlet bore 70 in housing portion 10A, with the fluid entering the cavity being directed at impeller 24.

Abstract: In a photometric coagulation instrument a synthetic clot signal is generated so that the operation of the instrument can be checked without the need to measure the actual clotting time of a control plasma sample.

Abstract: The device comprises a transducer (1) which consists of two or more transducer layers (11) and (12) and which is connected to a transmitter circuit (2) which consists of a transmission network (21) and a control network (22) which comprises a first correction circuit (223) for the correction of the transfer function of the tranmission network (21). The transducer is furthermore connected to a receiver circuit (3) which consists of a receiver network (31) and an auxiliary network (32) which comprises a second correction circuit (323) for the correction of the transfer function of the receiver network (31). The correction circuits (223) and the (323) consist of an adder circuit with a number of inputs, each of which is connected to an output of a delay line (227i, 327i) whose input is connected to the output of an attenuator (226i, 326i).

Abstract: A particle agglutination reaction is detected with the aid of a reaction vessel of flow cell type having an inlet, an outlet and an inclined passage communicating the inlet and outlet to each other. A test liquid containing particles is supplied into the passage via the inlet and is retained stationary therein for a given time period. Particles descending upon an inclined bottom surface of the passage form at first a stable base layer due to regular steps formed in the bottom surface. When a particle agglutination reaction has occurred, a uniformly deposited particle pattern is formed on the inclined bottom surface, while in case of non-agglutination reaction, the particles descending upon the inclined bottom surface roll down along the base layer and are collected at the lowermost portion of the passage. By detecting the particle pattern formed on the inclined bottom surface, it is possible to detect the agglutination reaction accurately.

Abstract: The ultrasound apparatus contains a focusing device such as a lens or lens system for focusing ultrasound waves. It also contains an ultrasound detector for receiving the focused ultrasound waves. The detector includes a number of elongated piezoelectric detector elements. The longitudinal axis of these elongated elements are curved. The focusing device is an astigmatic focusing device and has a first and a second focal plane. The ultrasound detector is positioned in one of these planes.

Abstract: An ultrasonic sector scanner using rotating transducers includes a transducer support wheel having a circumferential rim surface with a plurality of recessed seats within the circumferential surface for receiving inwardly facing transducers. The wheel and recessed seats provide accurate alignment of the transducers and acoustic mirrors direct ultrasonic energy between the transducers and ports.

Abstract: The method of this invention comprises introducing the fluid biological test specimen and the reagent (e.g., latex spheres) into a reaction zone in the image cell, evenly mixing and incubating the mixture thereby forming agglutinated particles. After transilluminating the reaction zone and imaging the light beams transmitted therethrough on the image sensor, the dark areas formed on the surface of the image sensor are measured, preferably electronically. This procedure is repeated for a reference specimen and the total dark imaged area is compared with the total dark area obtained for the unknown specimen for qualitative determination.In order to obtain the concentration of the immunoreactive component in the unknown specimen, the foregoing procedure is repeated for at least two specimens with known antibody concentrations, one of which may be a negative control.

Abstract: Two ultrasonic wave beams of different frequencies are emitted into a body under consideration from different locations on a surface of the body and a scattered wave beam created at a scattering point in the body by the interaction between the two ultrasonic wave beams is received. The emitting locations of the ultrasonic wave beams and the receiving location of the scattered wave beam are caused to scan. Thus, the stress distribution in the body is measured on the basis of the received outputs resulting from the scanning.

Abstract: A method and apparatus for quantitatively determining a degree of agglutination of a suspension of particles or the presence of the agglutination thereof is disclosed, wherein a liquid which contains agglutinated clots, otherwise a substance or substances to be about to agglutinate is made to slowly transfer through a small tube, in course of which agglutinated clots and non-agglutinated particles separate from each other in the liquid, when a degree of agglutination of particles and the concentration of the substance to be tested herewith can be determined quantitatively through the detection of difference in the optical properties of both the accumulation layer of agglutinated clots and the suspension layer of non-agglutinated particles, or the change in the optical properties of either of the above two layers, in particular the suspension layer.