16

Elements of Pharmacy.

part I.

Oxygen

Ice melted in lbs.

Substances burnt, 1 lb.

consumecin lbs.

Lavoisier.

Crawford

Dalton.

Rumford.

Hydrogen - - - -

6

295

480

320

Carburetted hydrogen

4

—

—

85

Olefiant gas - - -

3-5

—

—

88

Carbonic oxide - -

0-58

—

—

25

Olive oil - - - -

3-5

148

89

104

93-073

Rape oil - - - -

—

—

—

—

124-097

Wax.....

3-5

133

97

104

126-242

3S

—

—

104

111-582

Oil of turpentine - -

—

—

—

60

Alcohol - - - -

—

—

—

58

67-470

Sulphuric aether - -

3-

—

—

62

107-027

Naphtha - - - -

—

—

—

—

97-834

Phosphorus - - -

1-5

100

—

60

Charcoal - - - -

2-8

96-5,

69

40

Suiphur - - - -

1-36

—

—

20

Camphor - - - A

___

— '

—

10

Caoutchouc - - -

—

—

1

> 42 I

From this table it appears that hydrogen gas would form thebest fuel, where a high temperature is required.

c. Percussion, as far as it applies to solid bodies, is anothersource of caloric. Smiths, for instance, are in the habit ofkindling their fires by means of an iron rod, which is smartlyand quickly hammered until it becomes red-hot; and sparksare produced by the collision of hard bodies, particularly offlint with steel. This effect appears to arise from condens-ation, or forcing the integrant particles of the bodies closertogether, so as to dislodge the latent caloric they contain, andgive it out in the form of sensible caloric. The specific gravityof iron is increased -052 by being hammered ; and it becomesso hard and brittle that it cannot again be heated by percus-sion, until it has been exposed for some time to a red heat inthe forge. By the collision of flint and steel the oxidizementof the steel is also effected, the sparks being small incandescentpieces of oxidized iron.

d. Friction is also a source of caloric. It is a well-knownfact, that a considerable quantity of free caloric is disengagedwhen two substances are smartly rubbed together; but the realsource of the caloric thus evolved, still remains undetermined.

e. Finally, mixture, or the chemical union of two substances,in many cases evolves caloric. This always takes place whenthe density or specific gravity of the mixture is gi'eater than themean of the substances mixed; as in the mixture of alcoholand water, or of sulphuric acid and water; and much caloric