708 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



thi-ee or four tons would have transpired 600 tons of water. Soils alwajs 

 contain much water, even in the tropics, and the avidity with which an 

 artificially dried soil attracts moisture from the air makes it one of the 

 most powerful drying substances known. The vegetation which can exist 

 on a surface of coarse gravel is very scanty. The finer the particles, other 

 things being equal, permeability to air and moisture not being checked, 

 the more fertile the soil. Two soils analj'zed, a few years since, one from 

 the Scioto Vallej', in Ohio, the other from Vermont, gave the same ingre- 

 dients, though the Vermont soil would yield only meagre crops of buck- 

 wheat once in two or three years, while the Ohio soil had produced yearly, 

 for many years, 50 to 80 bushels Indian corn per acre, without manure. 

 The only difference seemed to be in the fineness of the particles. Mechani- 

 cal analyses, or the separation of the soil into portions of different degrees 

 of fineness, first b'"' sieves, then by washing, has been suggested as a 

 means of measuring the relative fertility of soils, and in connection with 

 chemical analysis has given some excellent results. 



A finely pulverized soil worked to the depth of several feet will supply 

 the plants with a greater quantity of water, and the plant-food contained 

 in it, during hot and dry weather, than a shallow and less pulverized one. 

 Water rises in capillary tubes, and the finer the tubes, the higher it will 

 rise. Of all the constituent parts of a fertile soil, humus, ov vegetable 

 mold, attracts and holds the most water, and is the slowest to give it up 

 except to the plant. It also attracts and retains valuable gases, its own 

 decomposition affords carbonic acid, water and ammonia, besides increas- 

 ing friability, permeability, and that openness and crumbly character pos- 

 sessed by all rich and good soils. Its increase in the soil is therefore often 

 a matter of the highest moment. One of the properties of every fertile 

 soil is that of arresting the most valuable kinds of plant-food in their pas- 

 sage through it. The humus has this property, assisted by the clay and 

 mineral substances. Humus, like charcoal, which it resembles, is a pow- 

 erful disinfectant or consumer of decayed substances, hence is useful in 

 absorbing the valuable products of decomposition in a soil. As the passage 

 of water through a soil is productive of no harm, while that which runs 

 from the surface bears away much thatis valuable, soils should bo drained 

 either by nature or b}' art. Nature often drains her soils too well — often 

 not enough. 



A soil may contain all the ingredients necessary for fertility, be suflB- 

 cicntly moist, and still not be fertile unless air have free access. 3Iuch of 

 the vast amount of water transmitted through the plants, is obtained first 

 by the soil from the air. The more open and finely worked the soil is, the 

 more susceptible will it be to the free passage of air into and through it. 

 Such is the soil — a synonym of filth, yet it is the most efficient purifier of 

 unclean things. It furnishes from its never-failing storehouse the materials 

 which, transformed, fill our granaries. Toad our orchards, refresh and rt\joice 

 the heart of man. 



On motion of Mr. Carpenter, the thanks of the Association were ten- 

 dered to Mr. Weld, for his interesting and instructive lecture, and a copy 

 •was requested for the use of the Association. 



On motion of Mr. Carpenter, it was resolved, that an exhibition of straw- 



