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The French press is a popular device for brewing coffee, comprising a cylindrical beaker -or 'jug' -fitted with a lid and plunger with a fine wire mesh filter. The plunger is used to drive the solid coffee particles to the bottom of the jug, separating these grounds from hot liquid above. When using the French press in this way, a growing permeable pack of ground coffee is pushed through hot water by applying force to the plunger. We use a combination of kitchen-based and laboratory experiments to determine the force required to push on the plunger as a function of the speed of the plunger and the mass of coffee used. We calculate that for the recommended preparation method, the maximum force is 𝟑𝟐 N to complete the pressing action in 50 seconds. We propose that home coffee preparation provides a fun, low-cost, and relatable learning opportunity for students and for those who are interested in coffee science.

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.Pe rme ability is a macros copic prope rty of mate rials with a pe rcolating pore phas e , s uch as many rocks and filte rs . We de s cribe a s imple e xpe rime nt for the e mpirical de te rmination of permeability using a low-cos t me thod s imilar to that us e d by Darcy. We advocate the us e of controlle d cylindrical sintered filters, for which there is theoretical constraint of the pe rme ability as a function of poros ity, agains t which e mpirical re s ults can be compare d. The me thodology pre sented he re provide s a s te p-by-s te p approach to laboratory e xpe rime nts and nume rical te chnique s for fitting a line ar e quation to data, and is appropriate for unde rgraduate Phys ics , Earth Scie nce , or Engine e ring cours e s .

Volcanic lakes are often associated with active geothermal circulation, mineral alteration, and precipitation, each of which can complicate the analysis of shallow magma physics, geophysical signals, and chemical signals. The rheology of the lake and associated hydrothermal system affects the eruptive activity as bubbles ascend and burst through the lake producing distinct ejection behavior. We investigate such phenomena by conducting scaled experiments in which heated water‐clay suspensions are decompressed rapidly from relevant pressures. After a jet phase of expanding vapor, the suspensions break up into ejecta that are either angular or droplet geometry. We parameterize these regimes and find a universal clay volume fraction of 0.28 below which the ejecta are form droplets and above which the ejecta are angular. We propose a regime diagram for optical observations of active lakes, which allows rheological characterization and informs volcanic monitoring.

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