Abstract: According to the present invention, a method and device for detecting failure of heating elements in various jets of a thermal jet printing device is provided. The printing device which includes a plurality of thermally actuated printing jets, each of which jets includes a resistance heating element, is actuated when a current is supplied to generate a bubble. The bubble expands eject a drop of ink. Electrical circuit means are provided including power supply means to supply current to the electrical resistance elements. Control means are also provided to selectively connect the elecrical resistance elements to this power supply in preselected arrays for forming bubbles in selected configuration to perform the ink jet printing. The operation includes a test circuit coupled to the resistive heater elements and operable by the control circuit to generate a failure signal representative of a resistance above a preselected value in any resistance heating elements.

Abstract: Method and apparatus for producing an N.M.R. picture of a plane through an object by isolating the plane using an oscillating gradient and interrogating the plane using a rotating gradient and a multiplicity of R.F. pulses which are averaged over a defined period to produce an average response which is used to produce the N.M.R. picture.

Abstract: Organic phosphate solvents used in the extraction of phosphoric acid from impure phosphoric acid solutions, and from which the phosphoric acid has been stripped, are washed with an aqueous alkali orthophosphate solution to remove impurities, particularly silica, fluorine and organic impurities, from the solvent prior to re-use.