[ 303 ] 



LVI. On. Carlonate of Ammonia as a Manure. 

 To Mr. Tilloch. 



Sir, — J. WOULD beg leave to recommend to your agricultural 

 readers the use of the liquor produced in the distillation of coal^ 

 at the Gas Light Establishments, as a valuable manure. It con- 

 tains principally carbonate of ammonia; and this, according to 

 Sir H. Davy in his Elements of Agricultural Chemistry, quarto^ 

 page 297, was found to produce more luxuriant effects upon 

 some plants on which he tried it, than any other saline solutioo 

 he made use of. And he very justly observes, that this result 

 might be expected ; for carbonate of ammonia consists of carbon, 

 hydrogen, oxygen, and azote, the prir.ciples of which all vege- 

 tables are composed. But from the circumstance of this liquor 

 containing a little sulphur, there is another valuable property it 

 possesses as a manure. If it be diluted in the proportujii of one 

 gallon to three of water, and then applied, it will have the effect 

 of destroying insects and grubs which frequently prove so de- 

 structive to growing crops. In the proportion of one gallon to 

 sixteen or eighteen of water, it may be applied to all green crops 

 with effect. 



The tar that is produced in the same operation, when mixed 

 very largely with soil in the proportion of a gallon to about a 

 wheelbarrow of mould or marl, and this mixture used as a com- 

 post and ploughed in, or applied as a top dressing, will also be 

 found a most valuable and active manure. 

 I remain, sir. 



Your most humble servant, 

 April 17, 1815. C. D. 



LVI I. Proceedings of Learned Sodeiies. 



ROYAL SOCIETV. 



April 6. xx PAPER by J. Knox, Esq. was communicated by 

 Dr. Young, detailing a series of experiments on coloured con- 

 centric rings, by means of lenses, on a piece of plain mirror, or 

 ©n a table before a window. It appears, according to these ex- 

 periments, that the thickness and number of glass plates produces 

 the variety of coloured appearances. Thus, apiece of common 

 erown glass laid on a table opposite a window, antl a wire rod 

 held over it, the shadow is seen double ; with two pieces of glass 

 placed on each other in the same manner, the shadow appears 

 treble, with three pieces quadruple, and so on ; shadows always 

 increasing acconliiii; as the reflecting and refracting surfaces in- 

 crease. 



