More on cocktail thermodynamics

Debby found this post from Dave Arnold that resembles what I discussed in the last post. Shorter version: I’m probably wrong about the ice being close enough to thermal equilibrium for government work, but the explanation of what is going on isn’t quite the way I recall Weitz explaining it. And my old Intro Bio prof is still wrong.

Fact 1:Ice at 0°C can chill an alcoholic drink well below 0°C. This fact is counter-intuitive to many, but is an irrefutable consequence of the laws of thermodynamics.

Arnold does an experiment that is essentially what we saw on Friday night, using vodka instead of tequila. After pre-incubating ice in water, the water is drained off and vodka is added. He gets  slightly diluted vodka at -4.5 °C. He also did a measurement of how fast ice reaches thermal equilibrium:

Fact 2: Bar ice is almost always at 0°C unless it comes straight from the freezer. People have a hard time accepting this fact. As a test, I froze a large ice cube with a super-thin hypodermic thermocouple probe in the center.  I put that ice cube, along with some run-of-the-mill ice cubes for insulation, into a blast freezer for 4 hours until everything was at -20 C.  I then put the entire batch into a plastic container and waited.  In under 20 minutes, the large ice cube was within 0.5 degrees of zero.

In the comments to an earlier post, a reader wonders if he is measuring the core of the ice or surface water that develops around the temperature probe. Although the temperature might not be quite all the way up to zero for that reason, I suspect that the known conductive properties of ice mean that it’s closer to 0 than -20.

So why does this work and what’s wrong with my earlier analysis? Because I idiotically glossed over an important part of the Clausius version of the Second Law

Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time

The other change that is connected therewith to passage of heat is the breaking of bonds in the ice and the conversion of ice to water. Duh! As the vodka/tequila goes from 20 to 0, the heat is passing from the warmer liquid to the cooler solid ice, melting the latter with 333.55 J/g (80 cal/g). Melting a g of ice can chill 4 ml of water from room temp to 0.

But when the vodka/tequila is below 0 but above the depressed freezing point, melting reactions don’t stop. There are still a fraction of the total intermolecular collisions between the liquid and the ice that have sufficient energy to break the water-water bonds on the surface of the ice and melt off some of it (Not being an ideal gas, this won’t be a Maxwell-Boltzmann distribution, but there will be a mix of energies). This cools the liquid phase, just as it does when the collision occurs above 0°C.

Whether you are cooling water or liquor, the final temperature is still set by the freezing point, which is where the probability of a water molecule joining or leaving the crystal lattice is equal. So I think I’m still right that the freezing point depression is important. The ethanol isn’t doing anything to the heat exchange per se. It’s allowing us to see cooling below 0 when we measure the temperature of the liquid phase.

Arnold argues that the chilling is due to a combination of the heat that goes into melting and the entropic gain from diluting the water released by that melting into the liquid phase. In another comment he writes

Freezing point depression isn’t enough to explain why the drink gets colder than zero as you shake it. For instance, many oils have a very low freezing point but if you put an ice cube in them they will only go down to 0 degrees because there is no mixing.

I’m not crazy about this explanation, as it seems to me that it approaches Gibbs’ paradox territory with respect to the water released from the ice being diluted into the bulk vodka/tequila. Here, I think he’s seeing an effect of surface water around the ice cube limiting the temperature change. The observation about the melting points of oils does suggest a possible way to measure the internal temperature of ice cubes if one could suspend oil droplets in clear ice.

On the physical chemistry of ice cream and margaritas

When I was an undergrad at Stanford, senior biology majors were recruited to be TAs in the freshman biology class. I signed on for this and my first teaching experience at the undergraduate level involved attending lectures and leading discussion sections. In one lecture, the prof talked to the class about why salt is added to the ice in an old fashioned hand-cranked ice cream machine. He said, correctly, that the salt allowed the brine surrounding the freezing canister to get colder than 0°C, but that the mechanism was via the enthalpy of change solution of the salt dissolving in the water. I told my recitation section that the prof was wrong. The brine gets colder than 0°C due to freezing point depression, and that it was thanks to the ice starting at well below 0°C.

My questioning of his authority got back to the prof, who decided to add some material to a subsequent lecture to correct what he believed was his smart-aleck TA leading some of his freshmen astray. He pointed out that the enthalpy of solution for NaCl is +3.3 kJ/mol (or ~0.8 kcal/mol; we used kcal back then). I forget how much NaCl he thought was reasonable, but he came up with a back of the envelope calculation that disagreed with this

For each 58.44 grams (2.06 ounces) of salt that dissolves, 0.717 kilocalories (3 kilojoules) of heat is absorbed, meaning that dissolving salt causes the solution to become colder. The change is so slight you are unlikely to notice it in everyday life.

Fortunately for my prof, this was long before smart-ass students could use Google on their phones to find links to contradictory sources. And Wikipedia was far in the future. Saturated NaCl at 0°C is a 26% solution, which is ~4.45 M. So, starting with ice cold water with no ice you could drop the temperature to something on the order of 3 degrees. Which would eventually freeze the ice cream if you had massively excessive volume relative to ice cream, where you have to need a liquid to solid phase transition where the enthalpy of fusion on the order of 200 J/g (less than water, but still a lot relative to the heat of solution, according to this (pdf)).

So, in hindsight, I remain unconvinced by my old prof. I’ve often thought that one problem with intro bio textbooks is that they start with material that is taught more rigorously  in intro chem, by faculty who know the material better. I might have only been a freshman, but the elapsed time between when I had taken chemistry was decades shorter than it was for the ecologist teaching intro bio.

I was reminded of this experience earlier on Friday night, when I attended a very entertaining public lecture in the Physics Department, only peeking at the streaming video for the Stanford-S. Carolina Women’s basketball Final Four game on my phone a couple of times (Stanford lost, unfortunately… not enough enthalpy of shooting).

This was the event:

Now Harvard’s David Weitz is very different in background from a Stanford Ecologist/Intro Bio prof., and the elapsed time from my last physics/p. chem course is orders of magnitude longer than the last time he taught physics. Nevertheless, I think he made the same kind error as my old Intro Bio prof, and in fact I think his is worse in terms of the thermodynamics.

Toward the end of the lecture, he was using Peter Madden’s margarita preparation to illustrate temperature and phase transitions. In a shaker with ice and water, he asked the packed audience what they thought the temperatures were for the liquid and solid phases, i.e. the water and the ice. A young boy in the audience guessed that because they were in different phases, the ice was colder. He said something like: the ice is 31.999999 °F and the water is 32.000001 °F. Weitz said, no, they are both at 32 °F (or 0°C; there was a lot of shifting between C and F and I forget which). At that point, I leaned over to Debby and muttered that he was assuming that the system had reached thermal equilibrium, which was not knowable from the information provided.

OK, whatever… but then he had Madden pour out some tequila, which the measured as being at room temperature. They drained the water from the shaker, added the room temperature tequila, and shook it to mix. He then asked what people thought the temperature of the tequila would be. People guessed, they did the measurement, and lo and behold, it was significantly below 32°F/0°C.

What gave me a deja vu experience was his explanation of why the liquid phase was below the freezing point of pure water. We agree that the ethanol in the tequila is key. But unless I really misunderstood him both in real time and when I asked him about it afterward, he was arguing that the ethanol somehow allowed the liquid phase to lower the temperature of the solid phase! Which would require heat flow from the colder ice to the warmer tequila, looks to me like a flagrant violation of the Second Law of Thermodynamics.

This violation is only a problem if you think, as he insisted afterward, that the ice in the ice-water mix had reached thermal equilibrium and the solid phase starts uniformly at 0°C when the 20°C tequila is added. By contrast, if you agree with the kid in the audience that at least part the ice was colder than the final temperature of the liquid phase, there is no problem. The final temperature is just set by the freezing point depression from the ethanol and other solutes in the tequila.

The alternative hypothesis is that I’m misunderstanding what he said or missing something. This is plausible, because although it’s an appeal to authority argument, I think it’s a reasonable to think that a Harvard Physics Prof who specializes in phase transitions to have a higher probability of being right about this than me, a molecular biologist/annotation maven. Although I would estimate that the probability of me being right is still higher than the probability of getting a reservation at El Bulli before it closed.

But see the next post for an update!

Equation of the post:

ΔTF = KF · b · i,

  • ΔTF, the freezing-point depression, is TF (pure solvent) − TF (solution).
  • KF, the cryoscopic constant, which is dependent on the properties of the solvent
  • b is the molal concentration of the solute
  • i is the stoichiometry of the solute: the number of particles per molecule in solution. For ethanol this would be 1; for NaCl, it would be 2.

From Wikipedia.

RIP MagSafe power

I just got a new Slate Gray 13″ MacBook Pro with the touch bar. Overall I’m sure I’m going to like it just fine, but I have to say this:

Dear Tim Cook,

The MagSafe power connector was probably one of the best things you ever did for laptops… and it’s really annoying that you’ve killed it in the new MacBook Pro.


Slightly less annoying is that while the USB-C to Thunderbolt 2 adaptor fortunately worked for mounting the old laptop in Target mode, it doesn’t seem to work as a Mini DiplayPort.

GMO tech makes the Impossible Burger possible

… or at least economically practical.

Earlier this week I noticed a retweet of this event in my twitter feed:

Coincidentally, someone else posted this video about the Impossible Burger (which I hadn’t heard of before this week)

I always find stories about science and food to be interesting, and this even had a connection to my alma mater: the founder of Impossible Foods is Pat Brown of Stanford’s Biochemistry Department.

Via Google, I found some interesting things about the Impossible Burger. The video talks about their general approach of using analytical methods to figure out what constitutes the constellation of perceptions that we get when eating a particular food. But what this post is about is the secret ingredient: heme. When we talk about red meat, a lot of what makes it red is the iron in heme. I first learned about heme in any real detail at Stanford when I took intro biochemistry as an undergrad (back then the undergrads could take the same course as first year med students). Heme is found in myoglobin and hemoglobin, the major oxygen carrying proteins in muscle and blood. Heme is responsible for the “smoke ring” in BBQ. Heme is also found other proteins, and based on this story, it appears that Impossible Foods first tried to get heme from spinach chloroplasts. But I’m guessing that the yield was too low to scale up production, so they looked at another source.

Leghemoglobin is a heme protein that is made for nitrogen fixation. The Impossible Burger contains soy leghemoglobin, but it’s not actually made from soybeans, because the leghemoglobin is found in the root nodules, which are not normally harvested. Digging up the roots to get the leghemoglobin would negate some of the environmental benefits claimed by Impossible Foods, but it also is probably as economically inviable as getting heme from spinach leaves, if not worse. So to get the leghemoglobin, they cloned the soy protein into Pichia pastoris, a yeast used in biotech for protein overexpression. Here’s how Impossible Foods describes their ingredients:

The Impossible Burger is made from simple ingredients found in nature, including wheat, coconut oil and potatoes. We add one more special ingredient, called “heme.” Heme contributes to the characteristic color and taste of meat, and it catalyzes all the other flavors when meat is cooked. Heme is exceptionally abundant in animal muscle — and it’s a basic building block of life in all organisms, including plants. We discovered how to take heme from plants and produce it using fermentation — similar to the method that’s been used to make Belgian beer for nearly a thousand years. Adding heme to the Impossible Burger makes it a carnivore’s delight.

This struck me as kind of odd. Is there something special about Belgian beer fermentation that makes it more similar to Pichia protein production than normal beer fermentation? Belgian beer fermentation historically uses more wild yeast than others, but as far as I can tell from my reading, Pichia is not a desirable species in any beer fermentation, and the inoculum is going to be a pure culture, not the stuff falling off the cobwebs from a Trappist monastery.

The news coverage of the Impossible Burger has been pretty clear about the source of the heme. For example:

  • NPR:

    By taking the soybean gene that encodes the heme protein and transferring it to yeast, the company has been able to produce vast quantities of the bloodlike compound. Each vat of frothy red liquid in the lab holds enough heme to make about 20,000 quarter-pound Impossible Burgers. “We have to be able to produce this on a gigantic scale,” says Brown.

  • NYT

    Thanks to the addition of heme, an iron-rich molecule contained in blood (which the company produces in bulk using fermented yeast), it is designed to look, smell, sizzle and taste like a beef burger.

But what I don’t see is in either article is the three letter acronym with a lot of baggage: GMO. It’s understandable, but kind of a shame, IMO. Impossible Foods got applied to the FDA for their GMO-based heme to be Generally Regarded as Safe. Most scientists I know would agree with that for most, if not all, extant GMO foods. But if golden rice and virus-resistant plants for poor farmers aren’t enough to sway GMO fearmongers, vegan burgers for first-world foodies are unlikely to do much.

Speaking of GM burgers, it’s been 10 years since Nature Biotechnology published a report of GM cattle where the PRNP gene was knocked out. Will we ever see CJD-free meat in the butcher’s section? That one really is a previously impossible product made possible by GM technology.

Butternut squash ravioli

One of the things I wanted in our new kitchen island was enough of a counter overhang to stably clamp our hand crank pasta machine so I could try making fresh pasta. This is actually the second attempt – the first was used for making Carbonara, and it worked pretty well despite some improvisational changes to the dough mid-stream, but I didn’t blog it.  I was trying to use some old semolina flour we had in the pantry, but the eggless recipe on the bag didn’t work, so I added that dough to dough made with AP flour and eggs. The result was tasty but made too much pasta for the two of us and I couldn’t reproduce it if I tried.

There are many recipes for butternut squash ravioli online, and a lot of different ways to do the different steps. Sage brown butter sauce is popular (but I didn’t have any fresh sage on hand)

Basically, the plan is

  • Roast the squash
  • Make the dough while the squash is roasting
  • Make the filling while the dough is resting
  • Roll the dough and assemble
  • Cook and serve

Roast the squash

butternut squash
roasted butternut squash

There seem to be two broad schools for roasting the squash, which can be divided into peel before and peel after. If peeling before, it’s roasted as chunks/cubes. I decided to go with peel after. Cut a butternut squash in half. Salted the exposed surfaces, coated with olive oil, and roasted at 375F for about an hour. Threw in some unpeeled garlic cloves about 15 minutes from the end.

I scooped out/peeled the result, weighed out a pound and kept the rest as leftovers for another use.

Make the dough

After my improvisation in the unblogged pasta experiment, I decided to go with a 0.5x version of the Serious Eats classic fresh egg pasta.

  • 1 c AP flour
  • 1 egg + 2 yolks (and some of the separated white)
  • 1.5 tsp salt

I did this in a food processor instead of in the classic pile of flour with a well for the eggs on a surface.  Yes, cleaning the food processor is an issue, but the cats don’t try to crawl into it. Initially the mix was too dry to come together, so I added back about 1 egg’s worth of the egg white I had separated out. Packed into a ball and left to rest.

Make the filling

  • 1 lb roasted squash
  • 3 cloves roasted garlic
  • 0.5 onion sauteed in oil from the roasted squash
  • 0.3 c toasted pine nuts
  • 0.5 parmesan cheese, microplaned
  • Salt and pepper
  • ~1 egg white (left over from making the pasta dough)

Process it except the egg white, adjust seasoning, process in the egg white as a binder. Some recipes have eggs and others don’t. Since I had the extra white anyway, I threw it in. The filling was pretty tasty, but I forgot to add nutmeg, which might have been nice, and I think it was a bit on the wet side.

Roll the dough and assemble

pasta machine and dough
Pasta machine and rested dough

The side of our island away from the stove has a depression where we will eventually put some stools. This give an overhang of the quartz countertop that can be used for clamp-on kitchen gadgets.

ravioli assembly
Assembling the ravioli

The pasta machine is an Mercato Ampia* that I’ve had for over 20 years. I haven’t used it that much because it was a pain to find a place to clamp it. When I did use it, it was to make flat noodles. I’ve been a bit intimidated by trying filled pasta.

I rolled the dough several times through the widest setting and then successively through the narrower ones. I cut it in half when it got longer than the cutting board. I didn’t go all the way to the thinnest setting.

ravioli cooking
Cooking the ravioli
butternut squash ravioli
Butternut squash ravioli with expired sage brown butter and peas.

0.5 Tb of filling was scooped using a measuring spoon (we actually have one for that volume now). I brushed around the filling with water, folded the dough over and pushed the filling under the dough to form a central lump, trying to get rid of any trapped air. This is definitely something where I need practice. I’m also wondering if it’s easier to use two sheets instead of folding over one.

One lesson: a pound of squash is way too much for the amount of pasta I made.

Debby cooked the ravioli while I made a brown butter with some dried rubbed sage of indeterminate age and added some frozen peas for a vegetable and to quench the heat on the brown butter.  3 minutes past flotation was the target for cooking. Only one leaked!

The sage flavor didn’t really come through at all, but overall it was a very good dish that could still be improved. To my taste, the brown butter sauce is really rich and I might prefer these in a chicken stock in a style like tortellini in brodo.

I’m certainly encouraged to experiment more with pasta.

* The machine I have appears to be discontinued. The one at the link is wider, I think. And much more expensive.

Sous Vide circulator setups

The last post about making lemon curd shows my two immersion circulators, an original, no-longer available at US voltage, Classic Nomiku and an Anova Precision Cooker (bluetooth only). I’ve had the Nomiku a since Thanksgiving 2013, while I got the Anova about a year later as part of their Kickstarter release (I went in with a colleague on the discount for 2 deal).

Since then the market for circulators has moved on. With two units that are both doing fine (knock wood), I’m not in that market for us these days, but I like to see what’s new. Even though I’m not looking for myself, these are nice potential gifts. has a recently updated roundup of several of the units that are currently available. The newer wifi version of the Anova (their pick) continues to be one of the most popular, but the model that seems to be very trendy right now is the ChefSteps Joule (which I have not seen in person yet). If I was shopping for a new setup or looking to give one as a present, I think I would seriously look at the Joule.

Kenji Alt-Lopez at Serious Eats reviewed the Joule in October, and came up with a conclusion that is similar to what I’m hearing elsewhere. The Joule is awesome except… It’s smaller and more powerful than the Anova, is waterproof, and has a cool magnetic base in addition to a clip. If I had a Joule and was looking to use it in a nonmagnetic container, I’d probably just put something like our enameled cast iron heat diffuser in the bottom.

The “except” is that part of what allows it to be awesome is that it can only be controlled via wifi or bluetooth. This means an iOS or Android phone or tablet via an app, or an Amazon Alexa (Echo or Dot) voice recognition system.

This is a view of my two circulators in my 12 quart Cambro box. Neither touches bottom and the Anova rides higher.

The Joule has a lower minimum water depth than other circulators at 1.5″.  By contrast, it’s 2.5″ on the Anova and 3.5″ on my Nomiku classic.  The new Nomiku wifi is also 1.5″. But that number is more meaningful with the Joule, because it can actually sit on the bottom of the container, while the others are really the distance from the bottom of the circulator to the minimum line.

Why would you want to use less water? The obvious reason would be if you’re in a drought area like California, and it seems silly to heat 6 quarts of water to cook a couple of sous vide eggs. But it’s also sometimes nice to be able to have a precisely controlled double boiler, and for that application it helps if the mixing bowl you’re using can actually sit on the bottom so it doesn’t float or capsize. I’ve also done sous vide cooking in Mason jars that are not fully submerged.

The photo above point out a couple of interesting differences between my Anova and my Nomiku. One of the things people didn’t like about the Nom is the external power brick. It’s one of my least favorite parts about it too. But what you can see from the photo part of why the Anova and Nom aren’t waterproof: there are cooling vents on both of them. On the Nom they’re on the power brick, but on the Anova they’re right above the clamp and on the top.

I find myself wondering if some of the complaints about failing units from Anova are related to users getting water in those vents. I’d also note that since the Anova is available on Amazon and is the most popular circulator, it’s going to have more complaints just by mass action.

The setup you use can affect minor issues with how you use your circulator. I like to put my setup next to the sink to simplify filling the box and dumping the water afterward. In our kitchen the distance from the countertop is about 17″, which is a bit less than the current standard of 18″. From what I can tell from looking at various websites, there is a lot of variation from this distance, especially in older kitchens. There’s an under-counter light fixture to the left of the sink that makes the clearance even shorter. The extra bit of space when mounting in the 12 quart Cambro means that the top of the cooker runs into the light fixture. This will be worse with any pot taller than the 8.25″ height of the Cambro. Depending on your countertop material, it’s recommended to put a trivet under the container, so that will add some additional height. The Joule is much smaller than the other circulators out there.

Sweethome loves the clamp on the Anova, because it allows you to do things like this. The Nomiku is too long to clamp to most of our pots, except for the larger stock pots. But I find that the Anova’s screw based clamp makes it harder to move between containers, and to detach when filling or dumping water. I find that I leave the clamp attached and remove the Anova body instead of unclamping the whole thing.



Although I’d seriously consider the Joule if I was just starting with Sous Vide, I’m still very happy with my two circulators. Because the Cambro is my main container, I’m going to keep using the Nomiku as my main machine even though it does have some drawbacks compared to the Anova, such as humming when not running (I can leave the Anova plugged in, but the Nomiku is kind of annoying in standby mode due to the hum; I just unplug it). In addition to the clearance advantage, the Nomiku is a bit more powerful.

Last night I finally got around to stealing an idea from this hack to make the external power brick less annoying. A $3 package of adhesive backed Velcro had 2X what I needed to give the brick a removable mounting point on the Cambro. I also got a folding silicon trivet that matches the Nomiku’s color scheme.


Sous vide lemon curd again

About a year ago, I posted a mistake where I made lemon curd without butter. Since then, I made some with butter, but forgot to blog about it. Since I’m procrastinating some paper grading, I thought I’d try it again today. We also have some lemons that need to be used. Here’s what I did last time

  • 4 egg yolks
  • 0.5 c sugar
  • juice from 2 lemons
  • Some lemon rind scraped off with a microplane
  • There should have been 0.5 sticks of melted butter. Next time.

In my non-blogged version, I did this, melting the butter in a measuring cup hung off the rim of the Cambro box I use with my Nomiku. 

After blending stuff with my stick blender, I poured it into a couple of old jelly jars we had, where I ran into a drawback of the original Nomiku – the depth of water needed. I ended up using a small loaf pan to prop up the jars.

Today, Debby has the loaf pans at the annual cookie baking party. But I also have an Anova circulator that can work with less water.

Recipe review

I also thought that I might as well look at the ratios used by various lemon curd recipes. The non-sous-vide ones tend to use a much higher volume because most people don’t have really tiny saucepans. But as much as I like lemon curd, I’m not sure its good to keep it for long periods of time, so recipes calling for 8 eggs seem like overkill to me.

[table id=8 /]

It seems that the REMcooks recipe I used has more eggs than the others. There also seems to be some variation in the order of addition of the ingredients. Most, but not all, add the melted butter last.

The plan

  • juice of 2 lemons + some zest
  • 0.5 stick butter, melted
  • 0.5 c sugar
  • pinch of salt
  • 2 whole eggs

I’m going to try the whole eggs because they seem to be OK in the Ina Garten recipe, and because that’s all we have in the house after Debby took the rest of them to the baking party (yes, I could go to the store, but this is a lazy procrastination exercise, not an attempt to optimize). I’m melting the butter in the container that came with my stick blender so it will get mixed with the eggs first, not last.

I transferred the mix to a jar from some preserves and I put this in at 165 F, but a problem occurred pretty quickly. Not using a properly sealing lid, some thermal expansion pushed some of the mix over the top leading to a cloudy water bath, which is perfuming the setup to smell like lemon curd. I don’t think this should affect the final result though.

The Anova Culinary App

Since I’ve been using my Nomiku most of the time, I hadn’t gotten around to installing the Anova Culinary app on my phone. Pairing with the Anova was straightforward. I’m not sure how useful the app actually is, though, other than being able to set a cook time. As far as I can tell, it doesn’t display a countdown after the timer is set.

Because it’s Bluetooth class 4, it doesn’t seem to hold the pairing when I leave the kitchen with my phone, or remember the cooker when I get back in range if I’ve used another app.

Playing with the Anova and the app, it seems that if you set the time after a run has been set manually, the settings from the phone don’t really do anything unless you pause or stop what is already running.


Either the lower egg content, the order of mixing, or the something about the configuration meant that the cook was incomplete at the top of the jar after an hour, but the curd was set at the bottom. Returned to heat for another 30 minutes. The final result came out fine.

Remodeling 2016 – Pier and beam

The next step was to do the pier and beam foundation for the new laundry room. This started by drilling holes and pouring concrete around rebar to make the piers that support the whole thing. This is supposed to be better for our expansive clay soil than just putting down a slab that would shift and crack. Piers were poured around May 12 based on my photo timestamps.

img_1623.jpgOnce the piers were set, Stearns did framing for the beams. There’s an extra pier in the middle so the floor won’t bounce.

They had to wait until we had some dry days to pour the beams. There’s some kind of biodegradable cardboard boxes that go in the bottom of the forms. Eventually these decay away to leave a gap between the ground and the beams so soil expansion and contraction doesn’t lift and drop the structure. But you can’t pour the beams if the ground is too wet.img_1630.jpg

Eventually the weather cooperated.

May 24

May 29. You can see the holes for ventilation of the space below where the floor will go. One is close to the viewer, the other is on the far corner.