158 PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 



ready -formed ammonia would be. The idea is at least a plausible 

 one, and has been frequently put forward as a- reason for pre- 

 ferring particular manures, and though there are no very good 

 grounds on which it can be maintained, it seemed very desirable 

 to have it submitted to experimental proof, and for this reason 

 gelatine was added to the list of substances used during the 

 past year. 



The experiments were conducted in a manner similar to 

 those of 1864, and were founded on the principle of starting 

 from a definite quantity of nitrogen in its different forms ; but, 

 in place of using three separate proportions, and thus making 

 three distinct series of experiments by which the inquiry was 

 complicated without any proportionate advantages, one quantity 

 only was employed, and in such proportion as to afford a supply 

 of nitrogen equal to 56 lbs. of ammonia to the acre. 

 The substances used in the experiments were — 

 1. Peruvian guano ; a sample of fair though not of very high 

 quality, the composition of which was accurately determined 

 after it had been reduced to fine powder, and thoroughly mixed. 

 It contained — 



Water, 15-89 



Organic Matter and Ammoniacal Salts, 50' 11 



Phosphates, ....... 22*50 



Alkaline Salts, 10-04 



Sand, ......... 1-4(3 



100-00 

 Ammonia, .......... 16"51 



Phosphoric Acid in the Alkaline Salts 



equal to 5 - 89 of Phosphate of Lime, 2 - 85 



2. The ash of Peruvian guano, prepared by burning it until 

 it was nearly white. 



3. Uric acid obtained by boiling Peruvian guano with hydro- 

 chloric acid, until all traces of ammonia were removed from it. 



4. Glue. That used was the ordinary kin<l employed by 

 carpenters, and was purchased in the thin cakes with which 

 every one is familiar. Considerable difficulty was experienced 

 in bringing it into a condition in which it could be applied to 

 the land, for it was so tough that it was impossible to grind it 

 in a mill. After several trials, however, it was found that by 

 careful drying in a kiln for some time it became so brittle that 

 it could be reduced by crushing and pounding to a powder, 

 which, though rather coarse, was sufficiently fine for the pur- 

 pose. It contained 13'36 per cent, of nitrogen, equivalent to 

 3 6 - 22 of ammonia. 



5. Sulphate of ammonia. A very excellent example of the 

 commercial article was employed. 



The exact composition of all these substances having been 



