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Comment by jonbaer | Hacker News Reader

Is there any information on what caused it yet?

It appears that it was a chemical storage warehouse, which contained calcium carbide (among other hazardous chemicals). A fire broke out in the warehouse and firefighters were fighting the fire with water. When calcium carbide reacts with water it produces acetylene gas, which is highly explosive.

http://www.cnbc.com/2015/08/14/china-experts-focus-on-chemic...

Great link, I agree with the comment that if the carbide went off it could set off the ammonium nitrate. Basically a really really big car bomb at that point.

Wow, what a title: "Lei Jinde, the deputy propaganda department head of China's fire department"

I hope that's a translation error. Fire Fighters are the last people who should need a propaganda department.

The only difference between a "propaganda department" and a "PR department" is the word used in the title.

Some non-English speaking government officials are ignorant to the word's modern meaning.

https://en.wikipedia.org/wiki/Ministry_of_propaganda

> Some non-English speaking government officials are ignorant to the word's modern meaning.

Or, rather, in some parts of the world, the negative connotations (not actual a change in meaning) it developed in some places from popular association with the German use of the term hasn't caught on, so there is no perceived need to replace it with a new word with the same denotation that "propaganda" has had for centuries.

Nope. Go to a large Chinese police/tax building and you'll see a sign for the "Propaganda Department". Part of me respects them for being honest about it.

I think probably my (engineers in general?) distaste for "marketing" and "public relations" and "spin" is the propaganda (telling you what we want you to think) component that is often there. It sounds nicer if you say PR, and in the US we tend not to be quite so blatantly at odds with the facts, but PR and marketing are often trying to accomplish the same thing. At least the Chinese are honest about what they are doing.

It is so easy to forget how did the term Public Relations come into wide use.

> Due to negative implications surrounding the word propaganda because of its use by the Germans in World War I, he promoted the term "Public Relations".

https://en.wikipedia.org/wiki/Edward_Bernays#Life_and_influe...

For more I recommend the BBC documentary "The Century of the Self".

"Public Relations" was invented (and named) by Edward Bernays after "propaganda" got a bad name from the German's use of it during the First World War.

Otherwise, it's the same thing.

a list of suspected chemicals at the Tianjin warehouse:

https://www.washingtonpost.com/world/asia_pacific/firm-says-...

It also contained a bunch of oxidizers like potassium nitrate. In fact, I was a bit confused because I didn't pick up the calcium carbide -> acetylene generation, and just a huge amount of oxidizers wouldn't cause such an explosion without sufficient fuel.

Per the comment there is some speculation on carbide. Something I don't think anyone has done is try to get a spectrum reading off the fireball. Typically various chemicals burn at different wavelengths so perhaps a hint of what was burning might be discernible by analyzing the spectra of the resulting light. What I don't know is how accurately a cell phone camera can reproduce that spectra, or if there is a mapping function from camera to spectra.

I sincerely cannot wait for those quantum dot spectrometers to arrive inside our cell phones [1].

Edit: these things could've saved lives, specifically the firefighters.

[1]: http://newsoffice.mit.edu/2015/quantum-dot-spectrometer-smar...

Ok, that is really slick. I really really hope this gets incorporated into phones.

I want one!! I've always wanted a spectrometer!

>how accurately a cell phone camera can reproduce that spectra

Not accurately at all. In terms of spectrum analysis, they're essentially as useless as the human eye. You're trying to get information from a detailed continuous function that varies wildly all along visible wavelengths (and beyond), and all you get are three data points. In fact, I've already analyzed the spectrum and I can confirm: Yup, it's red.

I suppose you could try gathering the exact spectral response of each camera having filmed the same thing (something like this [1]) and combine the resulting data to attempt getting a more detailed spectrum, but it would be very difficult and likely to yield disappointingly vague results.

[1]: http://www.gamutvision.com/docs/images/Kodak_KAF-10500-CX_re...

The drone flyovers taken at night hours after the explosion show fires burning with multiple different spectra - white, blue, gold, orange and red fires all burning down below.

A total mess of chemicals.

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