SUL

SUL

( 168 )

phureous acid gas, then adding a small quantity(about Vo) of nitrous gas, which will imme-diately produce red fumes of nitrous acid gas,followed by a white dense vapour which gra-dually condenses on the inner surface of theglass in shining stellated crystals, and the airof the vessel again becomes transparent. If afew drops of water are then introduced, thecrystals dissolve with great heat, and the nitrousgas is again expelled, which directly changesas before into red nitrous acid vapour, and thesame round of chemical action goes on till allthe oxygen of the air in the vessel is exhausted,or till all the sulphureous acid gas is consumed.

The presence of water is essential to theformation of sulphuric acid, for if sulphureousacid gas and nitrous acid gas both perfectly drybe brought in contact, no action ensues t but

the least portion of moisture causes them tocondense into the solid crystalline compoundabove described ; and a little more water gene-rates liquid sulphuric acid, and the nitrous gasis expelled. Sometimes, in making the aboveexperiment, the decomposition of the nitrousacid gas proceeds further than the generationof nitrous gas, and produces nitrous oxyd. Itdoes not appear precisely what is the reason ofthis variety of effect •, but when it does occur itstops the further acidification of the sulphureousacid, as the nitrous oxyd will not spontaneouslyreabsorb from the air the oxygen which ithas lost.

We shall now give Mr. Dalton’s table of thestrength of sulphuric acid at different densities,the results of his own experience in this acid:for several years. c

Table of the quantity of'real'acid in 100.parts of liquid sulphuric acid, at thee

temperature of 00°.

Acid percent, by

Acid percent, by

Specific

Boil mg

weight.

measure.

gravity.

point.

100

unknown

unknown

unknown

81

150

1.850

620 ?

80

1 48

1.849

605°

79

146

1.848

590°

78

144

1.847

575°

77

142

1.845

560°

76

140

1.842

545°

75

1S8

1.83S

530o

74

135

1.833

515°

73

133

1.827

501°

72

131

1.8 19

487°

71

.129

1.810

473°

70

126

1.801

460°

09

124

1.791

447°

08

121

1.780

435°

07

118

1.769

422°

06

116

1.757

410°

05

113

1.744

400°

04

111

1.730

391°

63

108

1.715

382°

62

105

1.699

374°

61

103

1.684

367°

60

100

1.670

360°

58.6

97

1.650

350 0

50

76

1.520

290°

40

56

1.408

260°

SO

39

1.30+

240°

20

24

1.200

224°

10

11

1.10—

218

■* New System,