Can liquid contain information? Is there any principle in physics that would allow liquid to contain some kind of information - could we, for example, in theory, use a glass of water to save information? For example digital photo that could be saved and read from a glass of water? Is there any law against it? Could it be done - at least in principle?
Edit:
I am interested into adding the information to the liquid itself without adding other substances and devices to it. Is there an information we can add to a molecule or an atom, that could be preserved?
 A: Liquid itself can indeed store information, you can add some sort of coloring to it. But the information you obtain is very short, either it is colored or not.  A bit of information. You can also measure another macroscopic properties of the liquid, like temperature, volume, and others. But this information seems really short compared with what the size of a picture can be : 
$$4 \text{mBytes}= 4 *1000000 * 8 \text{bits}=32000000 \text{bits}$$ 
That is a pretty long number, by only measuring the macroscopic properties you can probably get to $2^{10}=1048$ bits. But that is not close to what we want. Besides we also need a computing machine to process pieces the information. 
The study of a physical system observing its macroscopic properties is called thermodynamics. 
But to obtain information from the atoms itself is really difficult, even tough they are a lot, around $6.023*10^{23}$, they are really difficult to manipulate. The Physics Nobel prize of 2012  was to manipulate individual quantum systems and that was in a totally empty environment. 
If you were to do it in a liquid, probably a particle will collide with your system and change the state of your system. There is a theory of physics that deals with individual particles, called kinetic theory of gases. This theory rely on the probability theory, so you are averaging overall. You are not manipulating individual systems. 
Another possibility will be to put some nano robots or something, but that seems pretty difficult. Something more realistic will be some kind of little electromagnetic receiver and transmitter, that will allow to store information 
A: The problem with this is that all of the available degrees of freedom in a glass of water are highly susceptible to thermal fluctuations. So although in principle you could try to store the information, for example, in the orientation of the water molecules, this information would be destroyed very quickly because these molecules are constantly colliding with each other, moving around and rotating. 
You normally want to find something that is not too susceptible to environmental fluctuations. For example, optical disks store information in the physical shape of some substrate, i.e. bumps and grooves on a hard, rigid surface. These structures are obviously much less affected by the environment because it takes much more energy than is available at room temperature to affect them significantly. 
A: In 
the very first computers mercury memory was used. 
The mercury was contained in a glass tube, 
the information was fed in by some piezodrive at on end, 
at the opposite end the information was read out. 
http://en.wikipedia.org/wiki/UNIVAC_I
A: here's something
In fact it does it's weird but everything in the universe has figments of memory,black holes don't destroy the whole star but it's information is stored on black hole
