Abstract: A night sight assembly includes a backsight and a foresight. The foresight has a glowing portion, while the backsight is in the form of a diffraction grating.

Abstract: Recovery of uranium from crude wet process phosphoric acid (WPA) by cation exchange using as cation exchanger a resin comprising active amino phosphonic or hydroxy phosphonic groups linked to a matrix. The operational steps comprise reduction of uranium in the WPA to the tetravalent state, contacting the WPA with the cation exchange resin to load the latter with tetravalent uranium, displacing Fe.sup.+2 from the resin, washing the resin with aqueous ammonia, eluting the resin with a carbonate-bicarbonate solution and precipitating uranium from the eluate.

Abstract: A level comprises a sealed casing which holds a liquid and has a flat bottom end. It also includes a light admissive top section, bearing a periodic grating of alternating transparent and opaque stripes. A float is in the liquid inside a compartment of the casing underneath the light admissive top section. The float is capable of changing its position inside the chamber so as to retain its position relative to the horizon when the chamber is filled, and a mirror on the top face of said float.