+-----------------+-------------------+

Supposing it be desired to calculate the value of a manure by the first
column, it is obvious that if we suppose 100 tons to be purchased, the
per centages of the different constituents shewn in the analysis will
give the number of tons of each contained in 100 tons of the mixture,
and, selecting the analysis of the superphosphate given in a previous
page, we proceed in the calculation as follows:--

14.11 tons of organic matter at 10s. L7 0 0
14.86 " soluble phosphates at L30 446 0 0
15.13 " insoluble phosphates at L7 105 0 0
39.43 " sulphate of lime at L1 39 0 0
3.82 " alkaline salts at L1 4 0 0
2.10 " ammonia at L60 126 0 0
----------
Value of 100 tons L727 0 0
or L7 : 5s. per ton.

According to the second column, the numbers give the sum by which the
per centages of each ingredient must be multiplied, to give its value
in a ton of manure, and it is used for the same manure in the following
manner:--

14.11 organic matter, multiplied by 1-1/4d. L0 1 5
14.88 soluble phosphates " 6s. 4 9 2
15.13 insoluble phosphates " 1s. 5d. 1 1 4
39.43 sulphate of lime " 2-4/10d. O 8 10
3.82 alkaline salts " 2-4/10d. O O 9
2.10 ammonia " 12s. 1 5 3
--------
Value per ton L7 6 9

The difference is due to the less minute calculation of fractional
quantities in the latter case.

The calculation of the value of any other manure is effected in exactly
the same manner, taking care, however, to use the higher value for
phosphates in the case of a phosphatic guano. It will be obvious to
every one who tries the two methods that the first greatly exceeds the
second in convenience and simplicity in the calculations, and it is that
most commonly in use, although some persons prefer the second.

Although the data just given must always form the basis of the valuation
of any manure, there are a variety of other circumstances which must be
taken into account, and which give great scope for the judgment and
experience of the valuator. Of these the most important is the proper
admixture of the ingredients, and the condition of the manure as rega