Abstract: A method and an apparatus for precisely controlling flow rate of reactant solution such as silver nitrate solution or halide salt solution which is added into a precipitation vessel. The method comprises applying a pressure to each source of said two solutions and controlling both said applied pressure and a flow resistance of each feed lines of said two solutions so that each flow rate of the two solutions to be added into the precipitation vessel can be adjusted to a predetermined value.

Abstract: An impact-absorbing helmet comprising an inner, substantially-stationary, shell member formed as an integral part of the base member, including a separate outer shell member superposed over the inner shell member and rotatably attached thereto, the rotation thereof being about the vertical axis of the helmet, whereby any tangential impact received by the outer shell will cause the outer shell to rotate, thereby absorbing the blow thereto, wherein the outer shell is held in rotational, spaced relationship by a plurality of bearing units interdisposed therebetween.

Abstract: An angular impact-absorbing device applicable to auto bumpers and various types of guard rails, wherein the device comprises a first fixed body member secured to a substantially stationary support, a second movable body member slidably mounted to the first fixed body member, and bearing elements disposed between each body member, whereby angular impact received by the movable body member will cause the movable body to slide relative to the first fixed body and thereby absorb a substantial portion of the impact forces.