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meadow fescue, florin, and sweet-scented vernalgrass. I have examined the ashes of three of thesegrasses, meadow fox-tail, cock’s-foot, and florin.They contained a considerable proportion of gyp-sum.

Vitriolic impregnations in soils where there is nocalcareous matter, as in a soil from Lincolnshire, towhich I referred in the Fourth Lecture, are inju-rious ; but it is probably in consequence of theirsupplying an excess of ferruginous matter to thesap. Oxide of iron in small quantities forms anuseful part of soils : and, as is evident from the de-tails in the Third Lecture, it is found in the ashesof plants, and probably is hurtful only in its acidcombinations.

I have just mentioned certain peats, the ashes ofwhich afford gypsum; but it must not be inferredfrom this that all peats agree with them. I haveexamined various peat-ashes from Scotland , Ire­ land , Wales , and the northern and western parts ofEngland, which contained no quantity that couldbe useful ; and these ashes abounded in siliceous,aluminous earths, and oxide of iron.

Lord Charleville found in some peat-ashes fromIreland sulphate of potassa, i. e. the sulphuric acidcombined with potassa.

Vitriolic matter is usually formed in peats ; andif the soil or substratum is calcareous, the ultimateresult is the production of gypsum. In general,when a recent peat-ash emits a strong smell re-