340 Mr. Rice on the Weight of a Cubic Inch of Water, (Mav, 
ness of the experiments, and the subsequent change of mint 
standards. Capt. Kater has lately measured the length of the 
French standard metre, and found it equal to 39°37079 English 
longitudinal inches ; each standard being at its proper tempera- 
ture. Hence the cubic decimetre, or litre, will contain 61-0270554 
English cubic inches; now this bulk of distilled water was 
found to weigh, at its maximum of density and in vacuo, 18827-15 
gr. of the pile of Charlemagne ; and, therefore, one English 
eubic inch of distilled water, under like circumstances, weichs 
308°505 French gr. equivalent to 253°07148 English troy gr. ; 
and taking the expansion of water with Blagden and Gilpin, 
100094 : 1 :: 253°07148 : 252-8338. From this last number, 
which expresses the absolute weight of a cubic inch of water at. 
60° Fahr. let the weight of a cubic ineh of air at 60° ther. and 
30 bar. (generally accounted about 0°31 gr. but which will here- 
after appear to be more accurately 0°30519) be subtracted ; the 
remainder 25275238 will express the weight of a cubic inch of 
distilled water at 60° therm. and 30 in. barometrical pressure. 
I shall estimate it at 252°525 gr. (a number affording great 
facility in calculations), and endeavour to show that Sir George 
Shuckburgh’s experiments, and a theoretical view of the compo- 
sition of water, justify that choice. 
The first step here necessary is, from Sir George’s experiments 
made in Savoy (Phil. Trans. for 1777), to find the ratio of air to 
water when the barometer stands at 30 inches and Fahrenheit’s 
thermometer at 60°. In doing this, I shall not extend the calcu- 
lations further than two decimal places, as the experiment does 
not seem to have been made with sufficient precision to warrant 
greater nicety. Air and water were successively weighed in the 
same glass globe, or rather flask. 
The weight of its contents of air at 53° and 29°27 barometer 
was ascertained to be 16:22 gr. 
Its contents of water at 51° weighed 13562°6 er. 
From the expansibility of glass, it is evident that the capacity 
of the globe at 53° is greater than at 51°. Lhave calculated the 
difference produced by change of temperature on the quantity 
of air contained in the globe and converted into weight at about 
0-002 gr. which is, therefore, to be deducted from 16°22, leaving 
16-218, which becomes 16°38 when reduced to a mean temper- 
ature and pressure by the following proportions: 1058333 : 
1043749 :: 16:218 : 15°99, and 29-2717 (correcting for apparent 
expansion of mercury) : 30 :: 15°99 : 16°38. 
he buoyancy of air at 51° being greater than at 60°, a bulk of 
brass, whose weight is marked 13554 at the latter temperature, 
would at the former weigh about 0:03 gr. less; hence the actual 
weight is less at 51° than at 60° by 0-03 gr; the apparent weight 
is, therefore, to be diminished by that quantity. 
A bulk of water at 51°, equal to 13562°6 gr. will have ite 
