360 



IMPROVING FOOR SOILS. 



VI. 



On the Methods of improving Poor Soils, where Manufo 

 cannot be had. j&y John Alderson, M. D.* 



Observations -^^Y soil is generally understood so much of the earth's 



and enquiries surface as has been acted upon by the sun and air, and im- 

 respecUng the ^ ■, j. . . . , , ^ 



improTement pregnated irom time to time with the result of vegetable and 



pfpoorsoils» animal decomposition; but, as some plants will grow 

 where no such impregnation has taken place, we shall con- 

 sider this as mouldy and define soil, a compound of certain 

 proportions of the simple earths, of which Naturalists 

 reckon six or seven ; and as three of these generally pre- 

 vail, it will be quite sufficient for my purpose to note, that 

 these three are, chalk, flint, and clay. With chalk and 

 clay every person is acquainted ; and the common mode in 

 vhich flint affects the agriculturist, is in the form af 

 sand. 



All writers and experimentalists have agreed, that none 

 of these earths will, separately, answer the purposes of 



pfiHI which verge to the same point. In that, the general criterion 

 which was established to denote the influence of opium, was 

 founded on the observation of convulsions preceding death, and 

 the loss of irritability in the muscular fibre after death. The quan- 

 tity of this remaining was denoted by fhe frequency and strength 

 of the contractions upon the application of common salt. It was, 

 after many trials with other substances, found to be the most 

 ^certain and effectual test. The manner in which salt produces 

 this effect is no less beautiful than singular. It does not so much 

 appear to excite a muscle to contact, because a certain portion of 

 irritability is present, as it appeals to bestow irritability, if this 

 principle is not too much extinguished and the vitality gone. A 

 tnuscle which is incapable of contracting on the application of a 

 mechanical stimulus, and is relaxed and pale, will, on the ap- 

 plication of salt, exhibit very frequent and strong contractions, 

 assume gradually a beautiful florid colour, and will then become 

 obedient to other stimuli, to which before it was insensible. Thus 

 jt will be found to be a better restorer of irritability to the musculai: 

 fibre, than muriatic acid, related by II\uiiliolt. 



* Extract trom a Memoir read in the HoUlerness Society, and| 

 published by Harding, St. James's Street. 



agriculture^ 



