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and capable of carrying a quarter ampere without much heating, and R', a dial resistance-box in parallel with R. R', the resistance of which should be some thousands of ohms, serves as a fine adjustment. The current is allowed to flow for an exactly measured interval, say two hours, and kept adjusted by manipulating R' so that there is no deflection of G. The current is then calculated from the weight of silver, and when multiplied by the resistance S, gives the electromotive force of the standard cell.

TABLES

1. EQUIVALENT Weights (W) AND ELECTRO-CHEMICAL EQUIVALENTS

IN GRAMS (x) of Ions.
(The faraday is taken as 96,600 coulombs.)

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The following are from more recent experiments :

NOYES AND SAMMET, Zeitschr. phys. Chem. 43. 49 (1902).

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4. CONDUCTIVITY OF STANDARD SOLUTIONS (see p. 55).
5. EQUIVALENT CONDUCTIVITIES OF AQUEOUS SOLUTIONS

(see diagrams, pp. 60, 61). 6. IONIC CONDUCTIVITIES AT 18° (KOHLRAUSCH AND HOLBORN).

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O'001
O'002

65-3 44'4 35.5 64.2 5597 57*3 54.0 53.0 49 47.5 318 0'0001 64°7 43:8 349 63:6 55'4 55'0 51°7 50:6 47 45'1 316 O‘0002 64'4 43.6 347 634 55'1 54'3 51'0 50ʻ0 46 44.5 316 o'c005 64'1 433 34 4 63.0 549 5343 50'0 489 45 43.5 315

63*7 429 34'0 62'7 54°7 52.2 48.9 478 43 423 314

63'2 42.4 33.5 62.2 54'2 50*7 47'4 46°4 42 4099 313 0'005 62'3 414 32:6 61'2 53'2 | 48.2 | 44.9 4399 40 38.9 311

613 405 31.6 60 2 519 45°7 424 414 37 35'9 310 0'02 60'0 39'2 30°3 59'0 50'0 42°7 394 383 34 32'9 307 0'03 59'2 38'3 294 58:1 486 4095 37.2 36•1 32 30°7 305 0:05 57.9 37.0 28.2 56.8 46.6 37.7 34:4 334 29 27.9 302

55.8 35.6 26'1 54:8 4363 33.8 3095 294 25 24'0296

O'OI

O'I

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The above numbers serve to calculate approximately the equivalent conductivities of compounds of univalent ions, and of univalent with divalent ions (except H,SO.). For compounds of divalent anions with divalent cations the following table to be used :T. P. C.

S.

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coefficients (10)

18

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103

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O'0222

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Cl.

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66.40

Br.

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The limiting values 18 for infinite dilution at 18°, and the

I dl temperature coefficients

are (Kohlrausch and von

7 at Steinwehr, Berl. Akad. Sitzber, 26. 570, 581 (1902):Li. 33:44 O'0265 C,H,O,

25.7 0'0244 Na

43:55
0'0244

33:87

0'0234 Ag 54'02 0'0229 C,H,O,

35.0

0'0238 ΝΗ, , 54:4

F

46.64 0'0238 K. 64:67 0'0217

CIO,

55'03 0'0215 Tl. 66.00 0'0215

CNS

56.63 0'0221 Rb

676
0'0214 NO,

61078
Cs
68.2 O'0212

65.44

0'0216 H. 3180 Oʻ0153 I

090213

67.63 0'0215 Zn

0'0251
OH

174'0

O'0180 Mg

0'0256 Ba 5693 0'0238 SO,

0'0227 УРЬ

6105 0'0243 7. DISSOCIATION CONSTANTS K (calculated by Ostwald's equation from

the MOLECULAR conductivity). At 25°.
K X 10

K X 109 Formic acid 2104 m. oxybenzoic acid .

8:7 Acetic acid. I:8 p. oxybenzoic acid

2'9 Propionic acid

Ammonia
Glycolic acid

15'0
Methylamine

50'0 Malic acid 39:5 Ethylamine

56'0 Tartaric acid

Dimethylamine

74'0 Benzoic acid 6'0 Trimethylamine

74 Salicylic acid 102'0 Hydrazine

73 (See further, Chapter II.).

45-6 46'o

6897

I'3

23

6.6

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