It is supposedly of Turkish security personnel pouring Jenix, a pepper spray concentrate, into the water cannons they are using against protesters at Gezi Park.
Ansa (Italian) reports:
Istiklal Avenue, Taksim Square, Besiktas, the Bosphorus Bridge: names that trigger in the minds of millions the images of holiday tourists and colorful Eastern postcards. Today these places in the heart of Istanbul are war zones. A war, with lots of stinging substances used by the police, which continues into the night. Tens of thousands of people took to the streets again in the megacities of the Bosphorus and Taksim to march to denounce the brutal assault last night of police in Gezi Park and the young activists who occupied it.While Jenix doesn't seem to be any less legal than tear gas, it is still a chemical weapon that causes the skin to burn. it is unclear whether it is meant to be mixed together with water in this fashion.
A vicious attack, which injured 800, including children hit by rubber bullets, dozens of people 'burned' by stinging agents put in the water by police fire hydrants - as reported by the photos of the activists in which you can clearly see the cops load the substance 'Jenix' in armored vehicles - or hundreds suffocated by the clouds of tear gas. All this while riot police arrested the doctors who treated injured protesters, beat an opposition deputy, lawyers and journalists. It is a "war against the population," the president of the German Greens Claudia Roth charged.
So far, this has barely been reported in English anywhere except in social media.