1 2 AGRICULTURAL TEXT-BOOK. 



the air of towns, detected sulphuric acid, chlorine, and a Bub- 

 stance resembling impure albumen.* In a warm atmosphere the 

 albuminous matter very soon putrifies, and emits disagreeable 

 odors. By oxidation, this substance gives rise to carbonic acid, 

 ammonia, sulphuretted hydrogen, and probably to other gasses. 

 37. Mulder found free muriatic acid in the rain water of Am 

 sterdam, which he ascribes to the decomposition of the chloride 



This substance, vrhich has been noticed in rain and snow water by Feveral Chrm- 

 iflte, has recently been carefully examined by Dr. A. A. Hayes, of Massachusetts. 

 (Proc. ofAm.Assoc. of Science, 1850, B.pp. 207-212 .) It has been named Pyrrhx*. 

 Obtained from carefully filtered solutions, it appears as ft brown yellow adhesive sub 

 stance, having a strong oder of perspired matter, generally containing the remains of 

 animalcula, spores of fungi, and atmospheric dust. After its solution has been freed 

 from ammoniacal salts, the changes following in its fermentation produce ammonia. 

 Dr. Hayes is inclined to attribute to this substance, a powerful influence over vegeta 

 tion. When fertile soil is undergoing fermentation, the vapors, by condensation, af 

 ford a substance much like Pyrrhin ; but the state of admixture here renders it more 

 compound than when it is obtained from the atmosphere through the aid of falling 

 rain. To the falling of this substance from the air, Dr. H. attributes the remarkabta 

 growth of vegetation observed in New England and other places, when heavy rain 

 nceeeds a long continued period of dry weather in summer. &quot; The more fertile a 

 soil, either naturally or as resulting from judicious cultivation, the more the quantity 

 of matter, having the character of a ferment, we always find in our analysis.&quot; 



The following passage bearing on this subject appears in Silliman s Am. Journal 

 of Science and Arts, for September, 1853, page 273 . &quot; In continuation of his long 

 researches on the composition of arable soils, M. Verdeil and M. Rissler have recog- 

 uized in the aqueous extracts of these soils, the constant presence of a substance libs 

 angar ; and also a large proportion of mineral substances, little soluble or even insol 

 uble in water. Thus in 100 parts of aqueous extract, they found 49 of organic matter 

 and 54 of inorganic, consisting of sulphate, carbonate, and phosphate of lime, oxyda 

 of iron, alumine, magnesia, all insoluble in water (or scarcely soluble) ; and a the 

 presence of carbonic acid alone is not sufficient to explain the presence of these sub- 

 gtances in the aqueous extract, MM. Verdeil and Rissler have sought for the cause of 

 thig solubility, and concluded that it is due to the saccharine ingredients, for only a 

 Tery little water is required along with this sugar to dissolve largo quantities of inst^ 

 nble salts. They have recognized again the fact that nitrogen which enters into tha 

 composition of humus is found in the condition of an ammoniacal salt, and not in 

 that of an organic substance ; for they have collected the whole under the form of 

 ammonia in boiling the concentrated extract with milk of lime.&quot; 



We refer to this not as yet proving anything certain, but as a subject well worthy of 

 more investigation. There are many unexplained phenomena connected with vege 

 tation which may receive elucidation if these facts prove to be correct. The rapid 

 growth and change of color of plants after a thunder storm in summer has long been 

 noticed by the writer, and probably by most persons living in the country. 



