274 On the Application of Geology to Agriculture. 



tained by pursuing the methods recommended by Mr. Rham^, in 

 his article published in the first Number of our Journal (p. 46, 

 &c.) 



Sand . . . . 17-0 

 Clay , . . . .11-0 

 Car\3. Lime . , . 7*0 

 Humus . . . . 1*5 

 Loss , . . . 3*5 



lOO'O 



Here I may observe, that this mode of analysis (according to 

 my own imperfect trials, in which I was assisted by a chemist) 

 gives a very good mechanical division of the particles of the soil, 

 but not a chemical one, for it does not separate the clay from the 

 vegetable matter, as may be proved by the application of the 

 usual tests. * In testing the supposed portion of clay with sul- 

 phuric acid and potass, alumina was shown, and a sensible por- 

 tion of humus also. The same tests being applied to the humus, 

 several crystals of alum became visible, particularly when heated 

 over the spirit-lamp. 



There is probably more humus in the soil than is shown by 

 Mr. Rham's analysis. 



We burn chiefly the upper beds of this formation for lime, and 

 I find that the rock contains 93 per cent, of carbonate of lime, and 

 J per cent, of iron, the remainder being clay and silica, in nearly 

 equal proportions. My geological map at once points out all 

 those portions of the estate which consist of this stratum, and 

 upon which there is obviously no necessity for lime ; and I am 

 thus saved from the task which otherwise I should have to en- 

 counter of analysing the soil of each individual field. 



The above are a few of the more striking results which have 

 followed from the geological survey of my estate, and may per- 

 haps serve to show that, by pursuing a similar system over 

 different districts of our island, the knowledge of the regular 



* The observation is correct; the analysis which I gave in my prize essay 

 was confessedly only a mechanical separation of the constituent parts of a 

 soil. There is always a portion of humus left in the finest portion of the 

 clay, and also of the chalk, which adheres to it by cohesion, if not by a che- 

 mical combination. In the same manner some fine particles of earth are 

 washed over with the humus, however carefully the decantation may be 

 effected. But this does not invalidate the result, which is merely compara- 

 tive; and, with a little care, the proper correction is easily made. From 

 the proportion of sand in the soil above analysed, if it was taken some inches 

 below the surface, it is probable that the real quantity of humus does not 

 exceed 2 per cent. Some portion w'as probably included in the 3 '5 per 

 cent, loss, and carried oflf with the water used in the operation. This seems 

 not to have been evaporated to obtain the soluble portion. — W. L. Rham. 



It was NOT evaporated. — The Author. 



