Thursday, 24 October | 1861.
My dear Heinrich.
I am in want of a few volatile liquids: can you give me any. Boiling point up to 120oC. would answer.
Have you any body in your laboratory that would draw dry air for several days, by means of an aspirator over a quantity of fragments of onions placed in a glass tube, and who would determine what they had lost in weight by this process?
Have you any body who would perform this calculation for me:1 given the aqueous vapour of our atmosphere 1 per cent. Supposing the said atmosphere to fill a tube 3 feet long, and suppose the aqueous vapour to be condensed to a liquid plate of the same diameter as the tube, what would be the thickness of the plate of liquid?— Some of your physical pupils will perhaps work this out for me. I want it much.
Can you devise any means of getting a surface coated with soot without involving hydro carbons in the pores of the carbon?
Do you know of any experiments2 that have been made on musk to determine the loss of weight in a given time. They say it will continue to scent places for 20 years without losing any weight.
Answer me these questions if you can, and I will send you by and by an account of some results3 which will surprise you.
Yours ever | John Tyndall
RI MS JT/1/T/262
RI MS JT/1/TYP/7/2369
Please cite as “Tyndall1817,” in Ɛpsilon: The John Tyndall Collection accessed on