t'rom the Journal of Agriculture, and Transactions of the Highland and Agricultural 

 Society of Scotland, October 1851. 



Effects of Burnt Clay as a Manure. By Dr VOELCKER, 

 Professor of Chemistry in the Royal Agricultural College, 

 Cirencester. (Concluded from p. 79.) In burning clay properly, I 

 have found that a much larger amount of potash is rendered soluble, 

 in a way which I shall explain, after having given the details of 

 my analyses. But every physiologist knows that potash is one of 

 the most valuable and essential food of plants. I am inclined, 

 therefore, to consider the fact, that potash being rendered more 

 soluble on burning clay, is the chief cause of the beneficial effects 

 of burnt clay. 



I am indebted to Sir Thomas Tancred for the material with 

 which my experiments were made. 



Having procured for me some clay of the new red sandstone 

 formation from the farm of Huntstile, near Bridgewater, tenanted 

 by Mr Thomas Danger, I proposed to myself the following ques- 

 tions :^~ 



1. Is this clay more soluble after burning than in its natural 

 state ? 



2. What are the relative proportions of insoluble and soluble 

 matters in this clay, when burnt in different manners ? 



3. What is the relative composition of the soluble portion in 

 each case ? 



4. Is it essential or desirable that clays fit for burning should 

 contain lime ? 



5. What are the characteristics of clays, of which it can be said 

 that they are totally unfit for burning ? 



6; Can it be determined by chemical analysis whether burning 

 will be efficacious in rendering clay a fertiliser ? 



7. What are the reasons of the failure attending over-burning ? 



8. Does moderately burnt clay absorb more ammonia from the 

 atmosphere than unburnt clay ? 



9. Does over-burnt clay absorb any or no ammonia from the 

 atmosphere ? 



10. Is ammonia found in burnt clay, containing protoxide of 

 iron, when exposed in a moist state to the atmosphere in much 

 larger quantities than in the same clay exposed in a dry state to 

 the atmosphere ? 



11. What is the reason that burnt clays improve, especially root 

 and other green crops, as Mr Woodward states ? 



The nature of the chemical changes, which may be supposed to 

 affect the action of burnt clay on the land to which it is applied, 

 was examined by four distinct analyses. 



No. I. Clay-soil in its natural state. 



No. II. A quantity of the same clay-soil was exposed to a dull 



