Page:Proceedings of the Royal Society of London Vol 69.djvu/442

424 Experiment. 1 Density at C, 0-916335 Weight assigned. 3 2

. . 0-915460

2

3

0-916180

2

4

fO-915540

1

10-916060

2

Weighted mean ... 0-9160

We thus obtain 0*9160 gramme per cubic centimetre as the density of ice at C.

Four values for the coefficient of cubical expansion can be obtained from these results. They are :

Experiment. Coefficient of cubical expansion.

1 0-000155

2 0-000152

3 0-000153

4.. 0-000148

Mean 0-000152

The results of this investigation are that Nichols' value for the density of artificial ice is confirmed, but that since the same specimen of water can freeze into specimens of ice having different density, the use of the Bunsen ice calorimeter in absolute determinations must be limited to an accuracy of probably one in a thousand.

The expenses of this research have been in part defrayed by a Government grant from the Royal Society, and in part by the Cavendish Laboratory.

I wish to thank Professor J. J. Thomson, F.R.S., for his kind en- couragement, and my thanks are also due to Mr. E. H. Griffiths, F.R.S., through whom I was led to undertake the investigation.