226 
On the Theoretical and Practical Value of 
farm-produce, would be of a similar character, and approach In 
composition the fresh and rotten dung analysed by me, and 
consequently would contain very little ammonia, either in a free 
state or in the form of ammonia and salts. 
Now, if we express the whole of the nitrogen in dung in its 
equivalent of ammonia, and allow 8rf. per lb. for ammonia, and 
estimate the potash in the manure at the rate of 2d. per lb., 
soluble phosphate of lime at 2d., and insoluble phosphate of 
lime at \d. per lb. — which certainly are moderate rates for these 
constituents when they occur in concentrated artificial manures — 
and at these rates calculate the money-value of a ton of fresh 
and rotten dung, we obtain the following results. 
According to the preceding analysis a ton of rotten farmyard- 
manure contains: — ■ 
85 lbs. of sohible phosphate of lime, worth, at 2d. per lb. 
13 „ insoluble phosphate of lime, „ \d. ,, 
11 „ 2^otash, „ 2c?. „ 
I^itrogen equal to IG^ lbs. of ammonia, calculating ammonia at ] 
8(f. perlb 1 
Total estimated money- value of a ton of rotten dung .. 
In a ton of fresh farmyard-manure we have : — 
65 lbs. of soluble phosphate of lime, worth, at 2d. per lb. 
85 ,, insoluble phosphate of lime, „ Id. „ 
13 „ potash, „ 2d. „ 
Nitrogen equal to 17i lbs. of ammonia, calculating ammonia at| 
8c?. per lb. 
Total calculated money- value of a ton of fresh dung 
s. 
d. 
1 
5 
1 
1 
1 
10 
►11 
0 
15 
4 
s. 
d. 
1 
1 
0 
8i 
2 
2 
11 
8' 
15 7i 
It thus appears that if we estimate the money-value of good 
farmyard-manure according to the same rates at which the prin- 
cipal fertilising constituents in the dung can be bought in 
concentrated artificial manures, 1 ton of farmyard-manure would 
be worth in round numbers 15s. However, good dung can be 
bought in many places at 5.s. per ton, or one-third its estimated 
money-value ; and probably the highest price whidi a farmer 
would be inclined to pay for good dung would not exceed Is. Qd. 
per ton, or one-half its estimated money-value. The difference 
between the estimated money-value of farmyard-manure (calcu- 
lated at the market rate of the constituents when sold as con- 
centrated artificial manures), and the actual market price, ma} 
be fairly taken to represent the difference in practical valut 
caused by the greater expense of the carriage and applicatior 
of farmyard-manure, and the less vigorous action of -organi 
nitrogenous compounds as compared with ammonia salts. 
