The great part of the nitrogen of peat exists in an insoluble and inert form: but, by the action of the atmosphere upon it, especially when mixed with and divided by the soil, it gradually becomes available to vegetation to as great an extent as the nitrogen of ordinary fertilizers. It appears from late examinations that weathered peat may contain _nitric acid_ (compound of nitrogen with oxygen) in a proportion which, though small, is yet of great importance, agriculturally speaking. What analytical data we possess are subjoined. PROPORTIONS OF NITROGEN, ETC., IN PEAT. ---------+-------------+------------+------------+---------+------------ | | | Total |Ammonia, | | | Analyst. | Nitrogen. |per cent.|Nitric acid. ---------+-------------+------------+------------+---------+------------ 1--Brown | | | | | Peat|Air dry (?) |Boussingault| 2.20 | 0.018 | 0.000 2--Black | | | | | Peat| " | " |Undetermined| 0.025 |Undetermined 3--Peat |Dried at 212°|Reichardt[4]| " | 0.152 | 0.483 4--Peat | " | " | " | 0.165 | 0.525 5--Peat | " | " | " | 0.305 | 0.241 6--Peat | " | " | " | 0.335 | 0.421 ---------+-------------+------------+------------+---------+------------ Specimens 3, 4 and 5, are swamp (or heath) mucks, and have been weathered for use in flower-culture. 3 and 4 are alike, save that 3 has been weathered a year longer than 4. They contain respectively 41, 56 and 67 _per cent._ of organic matter. Sample 6, containing 86 _per cent._ of organic matter, is employed as a manure with great advantage, and probably was weathered before analysis. It contained 85 _per cent._ of organic substance. More important to us than the circumstance that this peat contains but little or no ammonia or nitric acid, and the other contains such or such a fraction of one _per cent._ of these bodies, is the grand fact that all peats may yield a good share of their nitrogen to the support of crops, when properly treated and applied. Under the influence of Liebig's teachings, which were logically based upon the best data at the disposal of this distinguished philosopher when he wrote 25 years ago, it has been believed that the nitrogen of a fertilizer, in order to be available, must be converted into ammonia and presented in that shape to the plant. It has been recently made clear that nitric acid, rather than ammonia, is the form of nitrogenous food which is most serviceable to vegetation, and the one which is most abundantly supplied by the air and soil. The value of ammonia is however positive, and not to be overlooked.