Abstract: A device for the production of a dental working model for preparation of a prosthetic work comprises a body member having a blind arcuated cavity bounded by facing inner and outer cavity walls, for receiving semi-liquid model material. The blind end of the arcuate cavity is closed by a sacrificial membrane which is integral with the body member. The membrane is of sufficient thickness to contain the semi-liquid model material within the arcuate cavity and of sufficient thinness to be easily removed, for example, by grinding.

Abstract: Apparatus for determination of the freezing point of a liquid or solution has a probe extending into the liquid with means for vibrating the probe. Fixed elements which are cooled, e.g. Peltier plates, are arranged adjacent probe so that a mantle of solid forms on these elements and grows to touch the probe, thereby changing the resonant frequency. This change in resonant frequency is sensed and used to control the cooling so that the probe remains just in contact with a surface where solid is forming, i.e. in liquid at the freezing point. The probe temperature is sensed electrically, e.g. with a resistance thermometer.