158 MANURE. 



referred to above, is substantiated by experiment. Sal- 

 ammoniac, or muriate of ammonia, and sulphate of ammonia, 

 were used by Kuhlmann as a top-dressing on mowing ground. 

 The field was apparently in the same condition in every part, 

 and equally exposed. It was laid out in plots of four square 

 poles, separated by trenches. Alternate patches were reserved 

 unmanared, and as the whole was in grass, all accidents of 

 culture were avoided. The season was rainy and quite wet. 

 The salts were applied at the rate of 240 lbs. per acre, and 

 the grass cut and cured on each plot at the same time. The 

 yield of hay, over unmanured plots, for every 100 lbs, of 

 sal-ammoniac used, was at the rate of 580 lbs. per acre ; 

 and for every 100 lbs. sulphate ammonia, 419.6 lbs. or as 1 

 to 0.723. 



This is nearly in direct ratio to the nitrogen, which, per 

 100 parts, in the muriate of ammonia, is 26.439 ; in the 

 sulphate of ammonia is 21.375; or the nitrogen is as 1 to 

 0.808, while the crop is as 1 : 0.723. 



In the same field, and at the same time, was used bone- 

 liquor, that which had been boiled on bones, to extract their 

 fat. The last being removed, the liquor is a weak solution 

 of glue or gelatin, containing, when dried, 16.980 parts of 

 nitrogen in 100. It was used at the rate of 2000 gallons per 

 acre. What, then, is the value of this bone-liquor, estimated 

 on the per centage of nitrogen? It is as 26,439 : 16.980. 

 Now 26.439 nitrogen in sal-ammoniac, gave 580 lbs. hay 

 excess over unmanured. Hence, 16.980 should give 372.8 ; 

 and this was the actual amount for every 100 lbs. of dry 

 matter in this liquor. Here, an organic manure, rapidly 

 decomposing, formed ammonia by its nitrogen, which afford- 

 ed a product equal, pro rata, to that of an easily decompos- 

 able salt, in which ammonia was already formed. 



Doubtless, had the salts employed been equally easily 



