440 On the fertilizing Properties' of Manures 



xnonia or the elements that compose it. Soot, well knowr*. 

 to be in small quantities a powerful encourage* of vegeta- 

 tion, contains much carbonate of ammonia, combined with 

 &)me of the carbonaceous parts, rendering them extractive 

 and soluble in water, forming a brown pungent liquid. 

 Pigeon dung is a dressing for turnip land in great request in 

 the North, where many hundred quarters are annually sold 

 at 121s. the quarter, though a very small proportion of the 

 demand is supplied. I have found, by experiment, that this 

 material is richly impregnated with carbonate of ammonia 

 as well as with the well-known element of ammonia, azote, 

 which, in the natural decomposition of the manure by putre- 

 faction, wheu committed to the earth, will be produced. 

 Rape dust is that particular part of the seed (left after the 

 oil is pressed out) which is intended by nature to corrupt, 

 and become the early cause or stimulus of the growth of the 

 embryo germ, and therefore contains the same element, and 

 which we can readily, by a chemical process, exhibit in the 

 ammonia which rape dust may be made to yield. It is hardly 

 necessary to mention urine, &c, from which ammonia i9 

 obtained in great quantity, or the dung of all animals, which 

 contains the same principle. It was from the dung of the 

 animals which fed on the fertile plains of Egypt that all the 

 sal-ammoniac known in commerce was for many centuries 

 obtained. From that country, the site of the temple of Ju- 

 piter Ammon, its name is derived. Soon after sal-am- 

 moniac became an article of European manufacture, it was 

 discovered that the bones and horns of animals yielded its 

 peculiar salt, that is to say, the ammoniacal principle, in 

 much greater quantity than their dung, and those parts were 

 aloi>e used to the exclusion of these: hence the name spirit 

 of hartshorn, given to the volatile alkali used in medicine. 

 It has been of late years discovered, that the scrapings, 

 shavings, and chips of the horns used in manufactures (par^ 

 tjcularly of the knife handles at Sheffield) are the most power- 

 ful and the best of all land dressings known ; and it is from 

 these very materials also that the greatest quantity of am- 

 monia is to he obtained, wool, silk, and hair excepted, ancj 

 these are again in great use in agriculture, when collected 



and 



