Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The most official water costs $120k a gallon

signoregalilei.com

Post reply on HN
Print view View original

71–80 of 196 posts

Re: The most official water costs $120k a gallon

#71

Post by htrp »

danbruc wrote: post #55
inigyou wrote: post #52

Earlier quoted context omitted.

You can centrifuge it. Heavier molecules move closer to the bottom. Repeat until you reach the desired purity. You need shitloads of ordinary water to extract a liter of heavy water. And I'd be surprised if there's any superheavy water in that, because tritium radioactively decays. Fun fact: Heavy water is slightly toxic to humans. If you only drank heavy water, you'd die as it shifts the chemical reactions in your b…

Another fun fact - heavy water has a sweet taste.

How did someone ever figure this one out?

Re: The most official water costs $120k a gallon

#72

Post by foobarian »

buildsjets wrote: post #64
cyphar wrote: post #31

Earlier quoted context omitted.

For more context, sample reference materials from the NIST reference catalogue are not meant to be exceptionally high purity examples of the sample -- SRMs are usually commercially-produced products. The real value is that each sample comes with a datasheet with incredibly detailed and accurate measurements that are (as you said) used for calibration of measuring devices in industrial settings. To quote a Veritasium…

Truth. I once paid nearly $500 for a set of 17 certified, calibrated wooden pencils, with documentation showing that each one met their rated hardness levels of 9H thru 6B. And for $500, they don't even come with erasers, that is an added-cost option. https://www.gardco.com/product/pencil-hardness-test-kit-astm...

Can I ask why :-) Sounds like an interesting project.

Re: The most official water costs $120k a gallon

#73

Post by selimthegrim »

tshaddox wrote: post #34
buildsjets wrote: post #9

Earlier quoted context omitted.

Cap your meal off with a NIST 1196a standard issue cigarette? I am told they taste like drywall and taxes. https://www.nist.gov/news-events/news/2020/02/nist-releases-... Perhaps you would prefer some standard issue meat. https://www.sigmaaldrich.com/US/en/product/sial/nist1546a

It's only $508 per cigarette: https://shop.nist.gov/ccrz__ProductDetails?sku=1196a&cclcl=e...

Now I wonder what the GOST ones were like

Re: The most official water costs $120k a gallon

#74

Post by mikewarot »

0cf8612b2e1e wrote: post #38
analog31 wrote: post #10

Earlier quoted context omitted.

I think that both the Celsius and Fahrenheit scales are now defined in terms of Kelvin and a formula. Most if not all of the units of measure are no longer related to their history except for an agreement to make the new units match the old ones at some point.

The US is technically metric in that the units are defined in terms of the metric equivalent. A US inch is exactly 2.54cm.

You can thank Carl Edvard Johansson[1] for that, the inventor of the gage block.[2]

He was the one who decided to make it a convenient value, according to Wikipedia[3]

  As a result of the definitions above, the U.S. inch was effectively defined as 25.4000508 mm (with a reference temperature of 68 degrees Fahrenheit) and the UK inch at 25.399977 mm (with a reference temperature of 62 degrees Fahrenheit). When Carl Edvard Johansson started manufacturing gauge blocks in inch sizes in 1912, Johansson's compromise was to manufacture gauge blocks with a nominal size of 25.4mm, with a reference temperature of 20 degrees Celsius, accurate to within a few parts per million of both official definitions. Because Johansson's blocks were so popular, his blocks became the de facto standard for manufacturers internationally, with other manufacturers of gauge blocks following Johansson's definition by producing blocks designed to be equivalent to his.
This makes it relatively easy to handle making metric threads on imperial machines, and vice versa, because you can use 50 / 127 gear tooth pairs to do the ratios.

[1] https://en.wikipedia.org/wiki/Carl_Edvard_Johansson

[2] https://en.wikipedia.org/wiki/Gauge_block

[3] https://en.wikipedia.org/wiki/Inch#History

Re: The most official water costs $120k a gallon

#75

Post by QuantumNomad_ »

al_borland wrote: post #57
vagrantJin wrote: post #46

Earlier quoted context omitted.

Celcius is pretty intuitive actually. It takes atmospheric pressure into account, Water is pretty abundant on the surface of the planet, and life kinda depends on it. It's a remarkable substance and quite stable. I dont think theres another substance where we can see all three phases with kitchen appliances and still consume it. Equally good for bathing and drinking. I need steam to clean clothes and cook my food. Us…

With all of those examples, the actual temperature doesn’t really matter. For drinking and bathing, people go by feel. In the kitchen, the freezer makes water freeze, and the stovetop will make it boil into steam, but exact temperatures aren’t really relevant here either. The same goes for ironing clothes, the iron just does it. When I think about where explicit temperatures are needed in the home, the oven and therm…

> When I think about where explicit temperatures are needed in the home, the oven and thermostat are the two things that come to mind.

But in that case in what way is for example baking a frozen pizza from the store at 400 to 425 degrees F more relatable/convenient/natural than 200 to 220 degrees C?

Re: The most official water costs $120k a gallon

#76

Post by jarenmf »

most needs for such water are for calibration of instruments - many labs run stable isotopes measurements which has many applications from tracing how plants use water to measuring your metabolic base rate .. so the main use case it to calibrate instruments because it's really difficult to have an absolute measurement of stable isotope ratios from first principles - and the ratios are so small you typically express them in relation to standards like VSMOW

Re: The most official water costs $120k a gallon

#78

Post by inigyou »

htrp wrote: post #71
danbruc wrote: post #55

Earlier quoted context omitted.

Another fun fact - heavy water has a sweet taste.

How did someone ever figure this one out?

Probably by drinking it. As I said, it's only slightly toxic. Cody's Lab has done it on YouTube. 0.01% of the normal water you drink is heavy water.

Re: The most official water costs $120k a gallon

#79

Post by GolfPopper »

masklinn wrote: post #62
georgeburdell wrote: post #48

Earlier quoted context omitted.

Yes, it’s a bit frightening to know what a hidden dependency NIST is on many things. In my industry, all calibrations ultimately derive from physical NIST standards for resistance, frequency, etc.

It’s frightening that… NIST is doing the very thing it was established to do back when it was called the Bureau of Standards?

I suspect the fear comes from both seeing NIST as a single point of critical failure, and perhaps also that it is a far less resilient and/or far more vulnerable, institution than may have been previously realized.
Post reply on HN