215 According to _Schübler_, the absorption of water by 100 parts of earth is, in the case of quartz-sand, 25 per cent. of its weight; for clay, 70 per cent.; for calcareous earth, 85 per cent.; humus, 190 per cent.; and for 100 parts of their value, respectively, 37.9, 66.2, and 69.2 per cent. The consistency of the four kinds of earth, in a dry state, is in the proportion of 0.100, 5, 8.7; their adhesion in a moist state, to iron agricultural implements, is in that of 0.17, 1.12, 0.65, 0.40. Of 100 parts of water mixed with these kinds of earth, the evaporation in four hours, at a temperature of 18° 75’ (centigrade) is 88.4, 31.3, 28 and 20.5 per cent, respectively. The diminution of volume when the moist earth dries, under the same degree of temperature, is, 0, 18.3, 5 and 20. Their relative absorption of atmospheric moisture for 48 hours is as 0, 24, 17.5 and 55; their absorption of oxygen in 30 days is respectively 1.6, 15.3, 10.8 and 2.03 per cent.; and, lastly, their heat-holding power is in the ratio of 95.6, 66.7, 61.8, 49. 216 In Austria, below the Enns, only 3.8 per cent. of the soil is barren; in the Tyrol, 29 per cent.; in Dalmatia, 48.1 per cent. (_Springer_). In the French Pyrenees, 43 per cent. is considered incapable of cultivation; in the Alps, in Landes and Morbihan, 42 per cent.; in the departments of Nord and Somme, 1.3 per cent. (_Schnitzler_). _Franscini_ considers 36 per cent. of Switzerland unfit for tillage. The idea “barren” is a very vague one, and hence a comparison of different countries on this point should not be made without great caution. _ 217 Wolff_, loc. cit., 353 ff. As to the manner in which soil and climate mutually improve or injure one another, see _Schwerz_, Prackt. Ackerbau I, 12. 218 In this respect, also, the fundamental difference between agriculture and industry is very important, inasmuch as the products of the former, equal in value to those of the latter, require a very large supporting or bearing surface; those of industry, a very small one. If _Nobbe’s_ “water-cultivation” should ever come to assume any great practical importance, agriculture would approach to industry in this respect. _ 219 Wolkoff_ has called special attention to mere _emplacement_: Lectures d’Economie polítique rationelle (1861), pp. 90 seq., 157 seq. _Bastiat’s_ rather broad and enthusiastic assertion, that no mere product of nature possesses value (in contradistinction to utility), an exaggeration of his very honorable contest with the socialists (1848!), is refuted by daily experience, as when, for instance, discoveries are made accidentally of metallic veins, coal-fields etc., which immediately acquire great exchange value.