30

SPECIFIC GRAVITY OF WATER AT DIFFERENT TEMPERA-TURES, THAT AT 62° BEING TAKEN AS UNITY.

70°

0.99913

56°

1.00050

44°

1.00107

68°

0.99936

54°

1.00064

42°

1.00111

66°

0.99958

• 52°

1.00076

40°

1.00113

64°

0.99980

50°

1.00087

38°

1.00113

62°

1 .

48°

1.00095

58°

1.00035

46°

1.00102

The difference of temperatures between 62° and39°, where water attains its greatest density, will varythe bulk of a gallon of water, rather less than thethird of a cubic inch.

And assuming from the mean of numerous estimates,the expansion of brass 0.00001044 for each degree ofFahrenheit’s thermometer, the difference of tempera-tures from 62° to 39°, will vary the content of a brassgallon measure just one-fifth of a cubic inch. It ap-pears that the specific gravity of clear water from theThames, exceeds that of distilled water at the meantemperature, in the proportion of 1.0006 to 1, makinga difference of about one-sixth of a cubic inch on agallon.

Rain water does not differ from distilled water, soas to require any allowance for common purposes.