In discussing the inter-action between the animal organism and the substances which act upon it, it may be well to take a slight glance first at the substances which compose its environment, although these will be afterwards considered more in detail.

Of the elements composing the earth on which we live we at present know about seventy-two whose existence appears well-established. They are given in the accompanying table. The atomic weights assigned to them cannot be regarded as absolutely correct. There are sometimes considerable discrepancies between those given by different authorities, and those which are accepted to-day may require to be altered again in accordance with the more exact knowledge which future observations may supply. There are slight differences between several of them as given in the British and United States Pharmacopoeias.

Table Of Elements

Element

Symbol

Valency or Atomicity

Atomic

Weight,

B.P.

Atomic Weight, U.S. P.

Atomic Weight very accurately determined1

*Aluminium

Al.

II. & IV.

27.0

27.0

27.009

*Antimony (Stibium)

Sb.

III. & V.

120.0

120.0

119.555

* Arsenicum .

As.

III. & V.

75.0

74.9

74.918

*Barium

Ba.

II.

137.0

136.8

136.763

Beryllium or Glucinum

Be or G.

II.

9.0

9.0

9085

*Bismuth

Bi.

III. & V.

209.0

210.

207.523

*Boron

B .

----

11.0

11.0

10.941

* Bromine

Br

I.

80.0

79.8

79.768

Cadmium

Cd

II.

111.8

111.8

111.35

Caesium

Cs.

I.

133.0

132.6

132.583

* Calcium

Ca

II.

40.0

40.0

39.99

*Carbon

C .

II. & IV.

120

12.0

11.9736

*Cerium

Ce.

IV.

141.0

141.0

140.424

* Chlorine

Cl.

I.

35.5

35.4

35.37

* Chromium

Cr.

II. & IV.

52.5

52.4

52.009

Cobalt

Co.

II. & IV.

58.9

58.9

58.887

Those marked with * are contained, either simply or in combination, in the British Pharmacopoeia. Those printed in italics are non-metallic elements. Their atomic weights are given as in the B. P.

1From Ira Remsen's Principles of Theoretical Chemistry.

Element

Symbol

Valency or Atomicity

Atomic

Weight,

B.P.

Atomic

Weight,

U.S. P.

Atomic Weight very accurately determined

Columbium vide Niobium

*Copper (Cuprum)

Cu. . .

II.

63.4

63.2

63.173

Didymium . .

Di. . .

IV.

145.4

144.6

145.4

Erbium. . .

Eror Eb1 or E

-

166.0

165.9

165.891

Fluorine . . .

F . . .

I.

19.0

19.0

18.984

Gallium . . .

Ga . .

IV.

70.0

68.8

69.9

*Gold (Aurum) .

Au . .

I. & III.

196.5

196.2

196.155

Glucinum vide Beryllium

Holmium . . .

. .

-

-

-

-

*Hydrogen . . .

H . . .

I.

1.0

1.0

1.0

Indium . . . .

In. . .

I. & III.

113.4

113.4

113.398

*Iodine . . . .

I . . .

I.

127.0

126.6

126.557

Iridium . . .

Ir . . .

II. & IV.

192.7

192.7

192.651

*Iron (Ferrum) .

Fe. . .

II. & IV.

56.0

55.9

55.913

Lanthanum . .

La. . .

IV.

139.0

138.5

138.526

*Lead (Plumbum)

Pb. . .

II. & IV.

207.0

206.5

206.471

*Litbium . . .

Li. . .

I.

7.0

7.0

7.0073

*Magnesium . .

Mg . .

II.

24.0

24.0

23.959

*Manganese . .

Mn . .

II. & IV.

55.0

54.0

53.906

*Mercury (Hydrargyrum)

Hg . .

II.

200.0

199.7

199.712

Molybdenum . .

Mo . .

95.5

95.5

95.527

Nickel . . . .

Ni. . .

II. & IV.

58.0

58.0

57.928

Niobium or Columbium

Nb . .

V.

94.0

94.0

-

*Nitrogen . . .

N . . .

III. & V.

14.0

14.0

14.021

Osmium . . .

Os. . .

II. & IV.

198.5

198.5

198.494

* Oxygen . . .

0 . . .

II.

16.0

16.0

15.9633

Palladium . . .

Pd. . .

II. & IV.

105.7

105.7

105.737

*Phosphorus . .

P . . .

III. & V.

31.0

31.0

30.958

*Platinum . . .

Pt. . .

II. & IV.

195.0

194.4

194.415

*Potassium (Kalium)

K . . .

I.

39.0

39.0

39.019

Rhodium . . .

Eh . .

II. & IV.

104.0

104.1

104.055

Rubidium . . .

Rb . .

I.

85.3

85.3

85.251

Ruthenium . .

Ru . .

II. & IV.

104.2

104.2

104.217

Samarium . . .

Sm . .

----

150.0

-

150.021

Scandium . . .

Sc. . .

----

44.0

44.0

43.98

Selenium . . .

Se. . .

II.

78.8

78.8

78.797

Silicon . . .

Si. . .

IV.

28.0

28.0

28.195

*Silver (Argentum)

Ag. .

I. (? II.)

108.0

107.7

107.7

*Sodium(Natrium)

Na . .

I.

23.0

23.0

22.998

Strontium . . .

Sr. . .

II.

87.4

87.4

87.374

* Sulphur . . .

S . . .

II.

32.0

32.0

31.984

Tantalum . . .

Ta. . .

III. & V.

182.0

182.0

182.144

Tellurium . . .

Te.

II.

128.0

128.0

127.96

Terbium . . .

. .

-

-

-

-

Thallium . . .

Tl or Th

III.

203.7

203.7

203.715

Thorium . . .

Th

IV.

233.0

233.0

233.414

Thulium . . .

. .

-

-

-

-

. Er, Roscoe and Schorlemmer, Treatise on Chemistry, vol. i. p. 54. Eb, Fownes, edited by Watts, 12th ed. vol. i. p. 401. E, Ira Bemsen's Principles of Theoretical Chemistry.

Element

Symbol

Valency or Atomicity

Atomic

Weight,

B.P.

Atomic Weight, U.S. P.

Atomic Weight very accurately determined

*Tin (Stannum) .

Sn. .

II. & IV.

118.0

117.7

117.698

Titanium . .

Ti . . .

IV.

49.8

48.0

49.846

Tungsten . .

W . . .

VI.

184.0

183.6

183.61

Uranium . .

U . . .

IV. & VI.

240.0

238.5

239.8

Vanadium . .

V . . .

III. & V.

51.3

51.3

51.256

Ytterbium . .

Yb. . .

-

172.8

172.7

172.761

Yttrium . .

Y . . .

IV.

89.8

89.8

89.816

*Zinc . .

Zn . .

II.

65.0

64.9

64.9045

Zirconium . .

Zr. . .

IV.

900

90.0

89.367