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1:06 sp. gr.

in equilibrium with water; if the acid is stronger, e.g. 1.02, the water
goes over to it; if weaker, e.g. 1.015, it goes to the water; at 22° C. it
most be diluted to 1.002 sp. gr. in order that endosmose may be directed
from it to water. (Dutrochet.) At 10° C. nitric acid of 1.09 sp. gr.
remains at the same level as water; if the sp. gr. be 1.12 or higher, the
water goes to the acid; at 1.08 sp. gr. and under, the acid goes to the
water. (Dutrochet.) Solution of oxalic acid goes over to water at all
degrees of temperature and concentration; the more it is concentrated the
faster it travels: on the contrary, it filters through the bladder much more
slowly than pure water (the slowness increasing with the concentration)
if the lower surface of the bladder be placed in contact with a solution of

the same strength as that whose rate of filtration is to be determined. hi This seems at variance with the supposition that endosmose is due to dif

ference of adhesive power. A solution of 11 parts of tartaric acid in 100
of water (sp. gr. 1.05) remains in equilibrio with pure water at 25° C.;
with a stronger solution the principal current is directed from the water
to the acid; with a weaker, from the acid to the water. At 15° C. equi-
librium takes place with a solution of 21 parts of tartaric acid in 100 of
water (sp. gr. 1.1); and at go with 30 of acid to 100 water (sp. gr. 1•15);
and at' + 0.25° with 40 acid to 100 water (sp. gr. 1:21). It appears,
therefore, that the tendency of the acid to go over to the water increases

as the temperature is lowered. A solution of 11 parts of citric acid in - 1:1

100 parts of water (sp. gr. 1.05) equilibrates with water just like a solu-
tion of tartaric acid." (Dutrochet.) Endosmose proceeds from water to
solutions of saltpetre and common salt. A solution of common salt of
1.12 sp. gr. rises in water twice as high in the same time as a solution of

A solution of common salt of 1.085 sp. gr. goes over to a
solution of Glauber's salt of the same density. (Dutrochet.) Endosmose
proceeds from water to solutions of common salt, chloride of calcium,
protosulphate of iron and sulphate of copper. The alteration of level
ceases when the liquids in both vessels become of the same strength.
With common salt the rising of the liquid is much less rapid than with
the more soluble chloride of calcium. If the experiment be made with
two solutions of the same salt of different degrees of concentration,
adosmose always proceeds from the weaker to the stronger. So like-
vise from the solution of a less soluble salt, such as sulphate of potash, to

aj saturated solution of a more soluble salt such as acetate of potash. ed Magnus, Pogg. 10, 160.) Endosmose proceeds from water to solutions 11

all kinds of salts, increasing in force with the strength of the solution;

is strongest with chloride of copper; then follow green and blue vitriol; til den common salt and sal-ammoniac; it is weak with chloride of iron and olphocyanide of potassium: with protochloride of tin, nitrate of silver, illud chloride of gold, which are decomposed by the bladder, no endosmose i observable. (N. Fischer, Pogg. 11, 126.) If the outer vessel contains

solution of sulphate of copper, the inner one water having a piece of
on in it, endosmose is directed to the water provided the iron touches

e bladder, while copper is deposited on the outer surface of the bladder,
id acid and oxygen carried over to the iron by galvanic action. (Fischer,
ilb. 72, 305, Magnus.) Zinc causes the water to rise as well as iron,
t more slowly; if the iron does not touch the bladder the water sinks.
iach. Schw. 58, 20.)

A bladder tied over a glass filled with alcohol, swells up under water to such an extent, that when the bladder is pricked with a needle, the alcohol spirts out in a long stream. (Parrot, Pogg. 10, 166.) In this

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experiment a little alcohol also passes into the water. (Magnus.) It follows, therefore, that alcohol and water exhibit contrary actions towards bladder and caoutchouc, because alcohol adheres more strongly to caoutchoue, water to bladder; water containing sulphuretted hydrogen penetrates into alcohol even more quickly than pure water. (Mitchell.) --For similar experiments by Sömmering see Alcohol.--Water passes to ether in the same manner as to alcohol. (Dutrochet.) Endosmose is directed from water to solutions of glue, gum, sugar, and white of egg; and when these liquids have the same density, 1.07, the rise of the liquid is measured in the case of glue by 3, of gum by 5, of sugar by 11, and of white of egg by 12: the last exhibits, therefore, the strongest endosmose. A solution of 1 part of gum in 16 of water passes over to a solution of 1 part of sugar in 16 or even 32 of water, although the former solution is much more viscous than the latter. If 1 part of oxalic acid is mixed with the solution of 1 of sugar in 16 of water, the endosmose is from the sugar solution to the pure water: when 2 parts of sugar and 1 of oxalic acid are dissolved in 16 of water the solution remains in equilibrium with pure water, portions of sugar and oxalic acid passing however into the water. A solution of sugar rises 3 times as high with solution of oxalio acid as with pure water in the same time; it acts in the same manner towards solutions of tartaric and citric acids. (Dutrochet.)

d. Stem of the Allium Porrum (leek). Endosmose from water to sulphuric acid of 1.0274 sp. gr. to solution of sulphuretted hydrogen, oxalic acid and tartaric acid of various degrees of concentration and at various temperatures; in the contrary direction, therefore, to that with bladder. (Dutrochet, Ann. Ch. Phys. 35, 393; 37, 191; 49, 411; 51, 159; extr. in Pogg. 138; 12, 617; 28, 359; also Ann. Chim. Ph. 60, 337.)

5. Adhesion between Solids. 1. Fine dust adheres to vertical and inverted horizontal surfaces.

2. Two heterogeneous bodies with very finely polished surfaces adhere together with a certain force. Comp. Prechtl. (Pogg. 15, 223.)

3. This kind of adhesion is most powerfully manifested when we the bodies is first brought to the liquid state (by which it acquires power of adapting itself perfectly to the surface of the other), and after wards solidified. This is the principle of glueing, pasting, soldering, si vering of mirrors, the use of mortars, cements, &c.

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GEOFFROY l'ainé. Des différents Rapports observés en Chimie entre diffé

rentes Substances. Mém, de l'Acad. des Sc. de Paris, 1718, 202;

1720, 20.
A. Marherr. Chem. Abhandl. von d. Verwandtschaft der Körper. Leipzig,

Wenzel. Lehre von der Verwandtschaft. Dresden, 1777.
L. Bergman. De Attractionibus electivis. Opuscula. 3, 291.
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wandtschaft. Erfurt, 1780.
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Hirschberg, 1792–1794.

Neuere Gegenstände der Chemie. Breslau. Heft 7–9. 1796
L. Berthollet. Recherches sur les Lois de l'Affinité. Paris, 1801.

Première et seconde suite des Recherches.
Troisième suite. Paris, 1806; also N. Gehlen, 3, 248.

Essai de Statique Chimique. 2 Bände. Paris, 1803.
Schnaubert. Untersuchung der Verwandtschaft, u. s. w. Erfurt, 1803.

On Chemical Combination and Decomposition. J. pr. Chem. rsten. Revision der Chemischen Affinitätslehre. Leipzig, 1803.

Relation of Composition to Form. Schw. 65, 320 and 394.
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Soc. Philom. 1809. 1, 298; also Gilb. 36, 6.

On the Precipitation of Metallic Oxides one by another.
Chim. 89, 21; also Gehl. 2, 487.
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vol. Manchester, 1808: translated into German by Wolff. Berlin,
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Ann. Phil. 3, 174; also Schw. 14, 462. Thomson, on Stoichiometry. Ann. Phil. 2, 32, 109, 167 and 293; 3, 134 and 375; 4, 11 and 83; 5, 184; 7, 343; 12, 338 and 436;

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5, 57.


16, 161 and 327; 17, 3; 18, 120. Further, Records of Gen. Sc.

1836, No. 15, 179; also J. pr. Chem. 8, 359.
J. J. Berzelius. 'Memoirs relating principally to Stoichiometry and

Electro-chemistry. Gilb. 37, 249 and 415; 38, 161; 40, 162 and
235.–Further, Schw. 6, 119.-Further, Ann. Phil. 2, 443; 3, 51,
93, 244 and 353; also Schw. 11, 419; 13, 240; 14, 446; 15, 277;
21, 307; 22, 51 and 317.-Further, Schw. 23, 98, 129 and 277;
also Ann. Chim. Phys. 11, 58, 113 and 225.–Further, Ann. Chim.
Phys. 17, 5.-Further, Ann. Chim. Phys. 14, 363; also N. Tr. 5,
2, 254.–Further, Pogg. 7, 397; 8, 1 and 177; 14, 558; 17, 379;
18, 74; 19, 326 ; 21, 614; 26, 320; 28, 388.

L'eber die chemischen Proportionen und die chemischen Wirkungen
der Electricität, nebst Tabellen über die Atomgewichte, u. 8. W.
Uebers von Blöde. Dresd. 1820.

Lehrbuch der Chemie. Ausg. 3. Dresd. und Leipz. 1833. 1, 3;
5, 3.
Prout, on the relation between the Specific Gravities and Atomic

Weights of Gases. Ann. Phil. 6, 321.
Meinecke. Chemische Messkunst. 2 Bde. Halle u. Leipz. 1815.

On the Densities of Elastic Fluids considered in relation to their

Stoichiometrical values. Schw. 22, 137.
Bischof. Lehrbuch der Stoichiometrie. Erl. 1819.
Bernhardi. Ueber Krystallogenie u. s. w. N. Gehl. 8, 360. Schw. 32, 1.

Sch, 37, 387. N, Tr. 7, 2, 40 B. 9, 2, 3.
Beadant on Crystalline Form and Chemical Composition. Ann. Chim.

Phys. 4, 72; also Schw. 19, 462.-Further, Ann. Chim. Phys. 7,

399; also Schu. 24, 110.-Further, Ann. Chim. Phys. 8, 5 and 14, 326.
Wollaston on Beudant. Ann. Phil. 11, 283; also Schw. 24, 102.
E. Mitscherlich, on Crystalline Form and Chemical Composition. Ann.

Chim. Phys. 14, 172; 19, 350; 24, 264 and 355.--- Further, Pogg.
12, 137; 25, 300.-Further, Pogg. 49, 401; also J. pr. Ch. 19, 457.

On the relation between the Specific Gravity and Atomic Weight
of Gases. Pogg. 29, 193.

On Action by Contact. Pogg. 31, 281.

Lehrbuch der Chemie. Aufl. 2, 1834. Berlin. 1,368, bis E. Turner on Chemical Equivalents. Phil

. Trans. 1829, 291; 1833, 5-
H. Buff. Lehrbuch der Stöchiometrie. Nürnb. 1829.
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Abth. 2.
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14, 305.
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Mag. Ann. 1, 411.
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22, 322. Fechner, on the Relation of the Law of Gravitation to the Doctrindiniform

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7, 344. J. Dumas, on the Atomic Theory. Ann. Chim. Phys. 33, 337; also Po

9, 293 and 416; also Schw. 49, 336 and 50, 215.

Affil imilar


J. Dumas, on Isomerism. Ann. Chim. Phys. 47,324; also Pogg. 26, 315.

Spec. Gr. of Vapours. Ann. Chim. Phys. 50, 170.

Leçons sur la Philosophie Chimique. Paris.
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Liquid and Solid Compounds. Pogg. 47, 133; 52, 243 and 262;

also Ann. Pharm. 36, 1. Ammermüller, on the same subject. Pogg. 49, 341. H. Schroeder, on the same subject. Pogg. 50, 552; 52, 269 and 282. Biot, on Atomic Chemistry. J. pr. Ch. 22, 321. L. Gmelin. Artikel-Verwandtschaft in Gehler's Physikalischen Wörter

buch. Ausg. 2, b. 9, s. 1857.

Synonymes: Chemical Attraction, Chemical Force, Elective Attraction,

Elective Affinity, Chemische Kraft, Verwandtschaft, Wahlverwandtschaft,
Wahlanziehurg, Affinitas, Attractio Electiva, A finité.

History. Chemical combination was in early times attributed to the general principle of Hippocrates that like assorts with like: hence the word Affinity (Verwandtschaft) which seems to have been first employed by Barchhusen. Becher assumed, in accordance with this dogma, that when two bodies are capable of combining they must contain a common principle. Others, among whom was Lemery, supposed that solvents are furnished with a number of sharp points by means of which they are more or less adapted to insinuate themselves into the pores of solid bodies and combine with them. According to Stahl's theory, chemical combination proceeds from the intimate approximation of the parts of the combining bodies but not exactly in the manner of a wedge. Newton was the first

ho referred chemical combination to the principle of universal attraction, (hough he at the same time partly assumed that this attraction between fultimate particles is not exactly the same as that which acts between the great bodies of the universe. Geoffroy the elder, in 1718, drew up the

irst Table of Affinity, which was subsequently enlarged and corrected by fellert, Wenzel, Bergman and Guyton-Morveau. The idea that many f-hemical combinations take place in definite proportions only had occurred o some of the older chemists, e.g., Wenzel, Bergman, Kirwan; and they endeavoured to determine these proportions. This view was confirmed by Richter, Proust, Gay-Lussac, Dalton and Berzelius, and expanded into the Theory of Definite l'roportions or Stoichiometry.

I. FUNDAMENTAL NOTION OF AFFINITY. Affinity is that kind of attraction by virtue of which bodies of disimilar nature combine together into a whole which appears perfectly finiform to the senses, even when assisted by the most powerful instruliments. The act of union is called Chemical Combination*, the resulting product a Chemical Comopund, and if it be fluid, a Solution. The dis

* The term Combination is sometimes also applied to the resulting product: the 199 esponding German word Verbindung is applied indiscriminately to the act of com

ition and to the product. [W.]


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