The Lizard Downs bear a short and green grass, 
which feeds sheep, producing excellent mutton ; 
and the cultivated parts are amongst the best corn 
lands in the bounty* 
That the theory which I have ventured to give of 
the operation of magnesian lime is not unfounded, 
is shown by an experiment which I made expressly 
for the purpose of determining the true nature 
of the operation of this substance. I took four 
portions of the same soil : with one I mixed -h of 
its weight of caustic magnesia, with another I 
mixed the same quantity of magnesia and a pro- 
portion of a fat decomposing peat equal to one- 
fourth of the weight of the soil. One portion of 
soil remained in its natural state : and another was 
mixed with peat without magnesia. The mixtures 
were made in December 1806; and in April 1807 
barley was sown in all of them. It grew very well 
in the pure soil ; but better in the soil containing 
the magnesia and peat ; and nearly as well in the 
soil containing peat alone : but in the soil contain- 
ing the magnesia alone, it rose very feeble, and 
looked yellow and sickly. 
I repeated this experiment in the summer of 
1810 with similar results ; and I found that the 
magnesia in the soil mixed with peat became 
strongly effervescent, whilst the portion in the un- 
mixed soil gave carbonic acid in much smaller 
quantities. In the one case the magnesia had 
assisted in the formation of a manure, and had be- 
come mild ; in the other case it had acted as a 
poison. 
It is obvious from what has been said, that lime 
u 8 
