I made the estimation scheme with Neural Network learning of this chart.

If you are lucky enough your browser support old JAVA and proper setting of JAVA option, you will see the window like below. If you enter temperature and click calc. button, the neural network estimate properties and plot Thermal conductivity (ThC) to Dnsity. You can copy the result showed text area to the other software if you use proper Java.policy.

If you select Density radio button, program plot density to presure.

If you can not see this window, please give up this old JAVA verson. (This Applet is still running with Mac with FireFox browser. 2011.11.15)