TRANSACTIONS OF THE SECTIONS. 43 
and he stated that a soil exhausted by long-continued cropping was found by him- 
_ self to yield to water twice as much alkali, after having been mixed with quicklime, 
as it had done before. 
Hence the frequent application of lime tends to produce exhaustion in the land, 
not only because it supplies in itself no fresh alkali, but likewise because, by ren- 
dering that which the soil contains more soluble, it causes it to be washed away 
more readily by atmospheric water. 
Ploughing, and other mechanical methods of pulverizing the soil, appear to act in 
the same way; and so also may we suppose to do the sprinkling of the soil with 
sulphuric acid, as is practised in some parts of the continent. 
The author then alluded to the various modes of explaining the advantage attri- 
buted to gypsum which certain leading agricultural chemists had proposed; one 
ascribing its virtues to the direct influence of the salt; another to the indirect good 
resulting from it, owing to its property of fixing ammonia; a third regarding its acid 
constituent as of the principal utility ; and a fourth its base. 
Dr. Daubeny gave reasons for rejecting the third and fourth of these hypotheses, 
but considered that the use of gypsum may be in part attributable to the first and in 
part to the second of the causes pointed out; supposing that this substance is gene- 
rally useful to all plantssfrom its property of fixing ammonia, and also especially 
serviceable to certain species, by supplying them with a salt which they require for 
their development. He was principally anxious however to bring forward this sub- 
ject, in the hope of inducing chemists to institute fresh experiments for the purpose 
of setting the question at rest. 
On the Fairy-rings of Pastures. By Prof. J. T. Way. 
A description of these patches, with which most persons are familiar, was given ; 
and it was stated that the grass of which such rings are formed is always the first 
to vegetate in the spring, and keeps the lead of the ordinary grass of the pastures 
till the period of cutting. If the grass of these fairy-rings be examined in the spring 
and early summer, it will be found to conceal a number of agarics or “‘ toad-stools” 
of various sizes. They are found situated either entirely on the outside of the ring 
or on the outer border of the grass which composes it. The theory of DeCandolle, 
that these rings increase by the excretions of these fungi, being favourable for the 
growth of grass but injurious to their own subsequent development on the same 
spot, was remarked on, and shown to be insufficient to explain the phenomena. A 
chemical examination of some fungi (the true St, George’s Agaric of Clusius—Agaricus 
graveolens) which grew in the fairy-rings on the pasture around the College at Ciren- 
cester was made. They contained 87°46 per cent. of water, and 12°54 per cent. of 
dry matter, The ashes of these were found to contain— 
Silicas.sssunsssssecdevessass.. “1°09 
Lime ....cecece phedintdeiouka® (1°35 
Magnesia. ......escsecsesees 2°20 
Peroxide of iron ......... trace 
Sulphuric acid ............ 1°93 
Carbonic acid ........ sexe 3°80 
Phosphoric acid ......... 29°49 
VOtAGE) sancisnmenpurpasesacs 00:10 
SOdA dsp asesateanccadeaceadne a a2 
Chloride of sodium ...... 0°41 
98°69 
The abundance of phosphoric acid and potash, existing no doubt as the tribasic 
phosphate of potash (3KO, PO5), which is found in these ashes is most remarkable. 
The author’s view of the formation of these rings is as follows :—A fungus is deve- 
loped on a single spot of ground, sheds its seed and dies: on the spot where it grew 
it leaves a valuable manuring of phosphoric acid and alkalies, some magnesia, and a 
little sulphate of lime. Another fungus might undoubtedly grow on the same spot 
again; but upon the death of the first the ground becomes occupied by a vigorous 
_ crop of grass, rising like a Phoenix on the ashes of its predecessors. It would thus 
