On Paring and Burniufj. 357 



character to any other on nvj farm. It Avas a very worthless pasture when it 

 came into mj^ hands, producing only coarse, wiry grasses and weeds. I had 

 it drained, then pared and burnt in the winter of 1847, since Avhich it has pro- 

 duced me a crop of oats, a crop of beans, and three crops of wheat, without 

 manure. The oats and beans were more remarkable for an enormous bulk of 

 straw than grain ; but the wheat in each case produced, with abundant straw, 

 forty bushels of grain per acre, though two of the wheat crops were in succes- 

 sive years. 



I am, "my dear Sir, yours very truly, 



Dr. VoeJclcer. Charles Lawrence." 



This clay, submitted to mechanical analysis, gave the following 

 results : — 



Hygroscopic (accidental) water .. .. 2'37 



Water of combination 5"38 



Carbonate of lime 3i'38 



Fine sand 2'25 



Clay 58-62 



100-00 



It Avill be seen that this is a calcareous clay, which, like most 

 clay-soils in the neighbourhood of Cirencester, contains but a 

 very trifling proportion of fine sand. 



The detailed analysis of the same clay, being well calculated 

 to illustrate the states of combination in which the constituents 

 of this and similar clays occur, may find here a fitting place : — 



Composition of Clay from Chesterton Farm, sent hy Charles Laivrence, Esq. 



Hygroscopic water 2-37 



Water of combination and a little organic matter .. 5-38 



Carbonate of lime 31-38 



e 1 1 1 [Carbonate of magnesia 2-04 



•' j-i t I Oxides of iron and alumina 11-90 



^^^^.^^^^M Potash -35 



^^^'l- Isoda -18 



fAlumina 7-43 



Insoluble J Magnesia in a state of silicate 1-52 



in acid. 1 Potash in a state of silicate 1'29 



iSilica 36-lG 



100-00 



By far the larger proportion of the potash, it will be observed, 

 exists in this clay in an insoluble condition as silicate of potash, 

 and as it contains much lime, which, as shown in my previous 

 communication, reacts upon the silicate of potash, when clays are 

 burnt at a proper temperature, causing the liberation of potash 

 and the production of silicate of lime, there is no doubt that this 

 clay is well adapted for burning, and in a burnt state likely to do 

 much good to light land. In its natural condition it yielded onlv 

 '35 per cent, of potash to very dilute acids, and after burning, 



VOL. XVIII. 2 u 



