Daniel Gabriel Fahrenheit research suggests that the Fahrenheit family originated in Hildesheim. Daniel's grandfather moved from Kneiphof in Königsberg (present-day Kaliningrad) to Danzig and settled there as a merchant in 1650. His son, Daniel Fahrenheit (the father of the subject of this article), married Concordia Schumann, daughter of a well-known Danzig business family. Daniel was the eldest of the five Fahrenheit children (two sons, three daughters) who survived childhood. His sister, Virginia Elizabeth Fahrenheit, married Benjamin Ephraim Krueger of an aristocratic family from Danzig. Daniel Gabriel began training as a merchant in Amsterdam after his parents died on 14 August 1701 from eating
Medical thermometer is less of a problem with a coloured liquid. In the 1990s it was decided that mercury-based thermometers were too risky to handle; the vigorous swinging needed to "reset" a mercury maximum thermometer makes it easy to accidentally break it and spill the moderately poisonous mercury. Mercury thermometers have largely been replaced by electronic digital thermometers, or, more rarely, thermometers based on liquids other than mercury (such as galinstan, coloured alcohols and heat-sensitive liquid crystals). Phase-change thermometers use samples of inert chemicals which melt at progressively higher temperatures from 35.5 °C to 40.5 °C in steps of 0.1 °C. They