56 



Essay on the Analysis of Soils. 



The result of various accurate analyses of soils shows that the 

 most fertile are composed of nearly equal quantities of siliceous 

 and argillaceous earths in various states of division^ and a certain pro- 

 portion of calcareous earthy and of humus in that state in which it 

 attracts oxygen and becomes soluble^ giving out at the same time 

 some carbonic acid. No chemist has yet been able to imitate the 

 process of nature in the formation of this substance ; and the cir- 

 cumstances which are most favourable to it are not yet fully ascer- 

 tained. Here is the proper field for the application of science 

 and accurate chemical analysis. 



As an example of an analysis may be useful to those who may 

 desire to try the proposed method^ we will add one actually made^, 

 under very unfavourable circumstances, and without any appa- 

 ratus. The only instruments at hand were scales and weights of 

 tolerable accuracy, three glasses, a foot long and IJ inch in dia- 

 meter, belonging to French lamps, a tin coffee- strainer, a piece of 

 fine gauze, and a very fine cambric pocket-handkerchief. A 

 little muriatic acid was obtained at the apothecary's. 



The soil to be analysed was taken from a piece of good arable 

 land on the south side of the slope of the Jura mountains in 

 Switzerland. Its specific gravity was taken as described before, 

 and found to be 2.358 nearly. 500 grains of the dry soil were 

 stirred in a pint of water, and set by in a basin. 



To save time, 500 grains more of the same soil were weighed, 

 after having been dried over the fire. It was well pulverised 

 with the fingers, and sifted through the coffee-strainer, then 

 through the gauze, and lastly through the cambric handkerchief. 

 Some portion was left behind at each sifting. The two first por- 

 tions were w ashed in the strainer and the gauze. The residue was 

 sand of two different degrees of fineness, which, when dried, weighed, 

 the coarser 24 grains, the next 20 grains. The earth and water 

 which had passed through the strainer and the gauze were now 

 strained through the cambric, and left some very fine sand behind, 

 which, dried, weighed, and added to what had remained on the 

 cambric when sifted in a dry state, weighed 180 grains. All that 

 which had gone through the cambric was mixed with water in a 

 jug and stirred about. The heavier earth subsided, and the 

 lighter was poured into one of the lamp-glasses which had a cork 

 fitted into it, and was placed upright. In about two minutes 

 there was a deposit, and the lighter portion was poured into a 

 similar glass, where it was left some time to settle. In this a 

 slower deposition took place, and in about a quarter of an hour 

 the muddy water was poured off into the third glass. The three 

 glasses were placed upright, and left so till the next day. In the 

 first glass was some very fine earth, apparently clay ; in the second 

 the same, but more muddy ; and in the third nothing but thin mud. 



