Abstract: A method for compensating for error in amount of indicator added to a sample under test in bleaching chemistry analysis involves adding a reagent system comprising an indicator and a dye in relative amounts such that the indicator at one wavelength (the "measuring" wavelength) and the dye at a different wavelength (the "reference" wavelength) exhibit the same absorbance at zero concentration of the parameter of interest. Error in the amount of indicator added to the sample is compensated for by measuring the decrease in absorbance at the measuring wavelength after reaction of the indicator with the parameter of interest, against the absorbance at the reference wavelength.

Abstract: A glass pH measuring electrode is mounted in a piston that reciprocates in a chamber which is in fluid communication with a reference electrode. Intake and outlet lines to the chamber are controlled by valves. A drive means operates the piston and the valves to pull successive liquid samples into the chamber for measurement and then to discharge them. The drive means also controls two positive displacement pumps, one of which feeds controlled amounts of electrolyte past the reference electrode and the other feeds a bacterial sterilizing agent to the chamber. The electrolyte flow past the reference electrode and into the discharge flow from the chamber maintains open electrical communication with the chamber. A deformable body, preferably a bed of finely ground methyl methacrylate grit, in the chamber engages and cleans the glass electrode as the piston reciprocates.

Abstract: A flask heater assembly for spherical bodied, boiling flasks in which a block is hollowed to receive the flask body and a ribbon of electrical resistance heated, flexible metal is folded into an elongated band and bent and fitted into the hollow to conform with the shape of the flask. A reduced voltage current is supplied to the ends of the ribbon to produce a temperature on the order of 400.degree. C., i.e., well below the glow temperature of the metal.

Abstract: A conductivity probe having a cylindrical body with an annular open-sided groove in which the electrodes are disposed, and a sliding cover wall for the groove biased to a position covering the groove but easily operable with one hand to slide the cover so as to open the groove. Viscous or slurried material can easily enter the groove, be trapped and confined for the conductivity measurement and then readily washed from the groove and surrounding parts for the next operation.

Abstract: A liquid sample is prepared for measurement of its calcium plus magnesium hardness by adding to the sample an aluminum chelate, preferably aluminum disodium (cyclohexylenedinitrilo) tetra-acetic acid, while maintaining the pH of the sample in the range between about 5 and 8. Interference by iron or copper ions is thereby substantially eliminated without using poisonous substances. The pH of the sample is then raised to between about 9.5 and 11 to insolubilize aluminum ions; a magnesium chelate is added to exchange calcium ions, releasing an equivalent number of magnesium ions; and a dye indicator that forms a colored complex with magnesium ions is added. The calcium plus magnesium hardness is then measured by titration or spectrophotometrically.

Abstract: A pipet for slurry and the like comprising a body with an end chamber containing a slidable element which, between them, defines a predetermined volume. The element includes an end plate to close the chamber, and a biased plunger is mounted in the body for moving the element so as to open and close the chamber and thus trap the predetermined volume of material to be sampled. The element is replaceable with one of different size to vary the volume of sample. In one form, a cutting edge on the body and a cutting surface on the end plate cooperate to sever fibrous material only partly in the chamber.

Abstract: An improved nephelometer comprised of a transparent cell for containing a liquid sample, a light source, and a detector is disclosed which reduces the amount of stray light reaching the detector. The cell is characterized in that either the illuminating light beam or the detected light passes through the cell wall face at an acute angle to the normal to the cell wall face.

Abstract: A mechanical strainer having a stack of alternate discs and blades biased together, the discs being slowly driven by a motor and the blades being anchored on the strainer frame, which discs and blades are perforated so that water surrounding the strainer can leak into the perforations of the stack. A passage is formed in the frame communicating with the perforations of the stack, and a tube leading to where the water is desired is coupled to the frame passage. The result is a kind of labyrinth rotary seal having intended leakage.

Abstract: A liquid dispensing device for chemical titration having a reciprocating plunger for expelling fluid from an attached titrating solution cartridge, and a lead screw for reciprocating the plunger whose rotation is measured and displayed by a digital rotation counter. The plunger can be selectively uncoupled from the lead screw to permit direct plunger positioning. A pair of manual knobs allow rapid direct rotation of the lead screw or slower, geared down rotation of the screw.

Abstract: A portion of a colorimetric liquid analyzer including a glass tube cell, a plunger mounted for reciprocation in the cell and having a passage to the cell, and a long liquid sample supply tube running from a body of liquid to be tested to the plunger passage. A "T" connector is provided in the tube and a pair of on-off valves which, together with the plunger, act to pump fixed volumes of fluid into and out of the cell. Means are provided to pump substantial air bubbles into the tube near its intake end, and the air bubbles are separated from the liquid through a vertical section of the T-connector so that only liquid is pumped into the cell. Preferably, acid is also added to the tube at its intake end to help dissolve particulate matter while the air bubbles continuously sweep the tube clean.

Abstract: An analytical method for determining the elemental carbon and nitrogen contents of a sample. The sample, as a liquid or in finely divided solid form is placed in an evacuable pressure vessel and is then oxidized with a cupric oxide oxidizing agent to convert carbon to CO.sub.2, nitrogen to N.sub.2, and hydrogen to water. After cooling to condense the water, the resulting pressure provides a measure of the total carbon plus nitrogen content of the original sample. An aliquot of the gas is then treated for CO.sub.2 removal, and the resulting change in volume thereby provides a measure of the ratio of carbon to nitrogen in the original sample.

Abstract: A method of colorimetrically analyzing even heavily turbid or already strongly colored water by first sensing transmitted light from a light beam through a sample of the fluid, adding color-producing test reagents to the sample, again sensing transmitted light from an identical light beam, and comparing the sensed light readings to detect the change, if any, produced by the added reagents. Two colorimetric cells are used, one for testing before the addition of reagents and the other after, with the cells being defined by glass cylinders in which pistons reciprocate to pump measured samples to the cylinders, clean the cylinders on each pumping stroke, and "valve" or block the light beam so that the other cylinder can be "read". Simple displacement pumps for the reagents, and the cell pistons, cooperate with valves defined by pincher arms squeezing flexible tubing to move measured amounts of sample and reagent throughout the analyzer.

Abstract: 3-(2-pyridyl)-5,6-bis(phenylsulfonic acid)-1,2,4-triazine and certain salts thereof, e.g.--sodium, are provided together with a method for forming such compounds. These compounds are useful as reagents in the spectrophotometric determination of iron in water or other solutions.

Abstract: 3-(2-pyridyl)-5,6-bis(phenylsulfonic acid)-1,2,4-triazine and certain salts thereof, e.g. sodium, are provided together with a method for forming such compounds. These compounds are useful as reagents in the spectrophotometric determination of iron in water or other solutions.