# How can the density of water be maximised?

What is the maximum possible density of water at room temperature? The density of the water in the Dead Sea at 37°C is 1.24. Would it be possible to increase the density using salts we add to our food, or possibly by using different salts than are present in the sea?

• I believe in your first sentence is a temperature too much and a density missing. What do you mean with homesalts? And I do not understand what "... and bringing some from out?" means. Could you please take a look and make your question a little clearer. Thank you. – Martin - マーチン Jul 17 '14 at 10:01
• True. What I meant was what salts could I use to increase the density would the salt that we add in food work or wel have to add the diffetent salts present in the sea. – user7063 Jul 17 '14 at 11:55

## 2 Answers

Clerici solution is a solution of equal parts of thallium formate and thallium malonate in water, density is 4.25 g/ml, Thoulets solution is solution of potassium-mercury iodide in water with density 3.2 g/ml. Don't even think of using them.

Sodium polytungstate $\ce{Na6[H2W12O40]}$ is a relatively safe compound and allows densities up to 3.1 g/ml. $\ce{ZnCl2}$ allows densities up to ~ 1.9 g/ml, but has acidic solutions.

Unfortunately, common nontoxic salts usually either are not dense enough or not soluble enough to make really heavy liquids, but densities around 1.1-1.2 g/ml are quite easy to achieve even with common salt. Note, however, that concentrated salt solutions 'siphons' water from human body through damaged skin and mucous membranes, and to some extent even through undamaged skin, which may lead to desiccation, trauma of mucous membranes and very unpleasant sensations.

• I wonder maybe sodium iodide would be a good option to go well beyond Dead Sea density with minimal fuss? It's dense, it's very soluble, it's fairly innocuous, it's a nutrient in microscopic quantities. Don't drink it or add it to food yourself, of course, it is not "salts we add to our food" in that sense. – Steve Jessop Feb 18 '15 at 12:25
• @SteveJessop Iodide solutions oxidize on air. Other than that, it gives solutions with density up to 1.8 g/ml. Pretty decent. – permeakra Dec 31 '15 at 17:04
• @prrmeakra I think the crystal structure of sodium polytungstate would be awesome. – Mockingbird Jun 29 '17 at 7:15

I think they use epsom salt (sodium sulfate) in the commercial isolation tanks designed to allow a person to float in water (i.e. salt solution) and meditate without having any tactile input (a phenomenon of the 70s, but I think there still are some around).
The more salt added to the water, the higher the density. Also, some salts are denser than others - so a heavy metal salt like cesium chloride would give a heavier water solution than say sodium chloride.