90 On the Inorganic Constituents of Plants, 



There are several points worthy of notice in these experiments, 

 amongst which is the effect of Muriate of Lime. In nearly all the 

 experiments which have been made at the Gardens, marked effects 

 have been produced by manures containing Muriatic acid ; hence it 

 was reasonable to conclude beforehand that the Muriate of Lime 

 would prove a good manure. Other considerations gave it a still 

 higher interest ; from previous experiments it had been ascertained 

 that a very small quantity of Muriate of Lime in a soil, exerted, in 

 consequence of its hygrometric properties, powerful influence on the 

 retentive power of the soil for moisture. It was, however, appre- 

 hended that the presence of any quantity of the salt, even though 

 small, might prove injurious to vegetation. The experiments above 

 described shew that this is not the case; the quantity employed 

 was considerable, and so far from doing any harm, it on the con- 

 trary produced a very excellent effect. 



The experiments on the hygrometric powers of soils, just 

 referred to, were part of an extensive series, undertaken with a 

 view of ascertaining what influence saline manures exert on the 

 retention of moisture. Weighed quantities of natural and artificial 

 soils of various natures were moistened, some with pure water, 

 and others with water holding in solution minute quantities of 

 different saline substances ; the soils were carefully weighed from 

 day to day, and the daily loss of water, subtracted from the 

 original quantity of moisture which the soils contained, shewed the 

 relative retentive power of the soil under examination. The 

 following short table shews the result of one of those experiments 

 in which twenty-five portions of fine siliceous sand weighing 2000 

 grains each, were each moistened with 500 grains of pure water, 

 and weighed every day. To the first five portions nothing but 

 the water was added, the next five received in addition one grain 

 of Muriate of Lime, the next five two grains of that salt, the 

 next five, five grains, and the remainder ten grains of the Muriate. 



