554 
Agricultural Statistics. 
called a good superphosphate, and which was probably sold at 
from 6/. to 11. per ton, it may not be lono; before such a sample will 
be considered of an inferior class. Of this I am sure, that the 
manufacturer must cease to leave any considerable quantity of 
phosphate of lime undissolved, and must raise the proportion of 
soluble phosphate to as high a pitch as possible. 
Note on the SoluUe Phosphates in Ouano. 
In the analysis of gnano it is usual to precijiitate the earthy phosphates 
from au acid soUition of burnt guano by means of ammonia. In the filtered 
liquid phosphoric acid is, however, still present, and in our analyses is deter- 
mined as phos[)hate of magnesia. It is this phosphoric acid tliat is mentioned 
as " phosphoric acid in the alkaline salts." It does not, however, follow that 
the phosphoric acid so determined should be in the soluble state in the guano, 
but I have proved that it is so, and generally in the proportion stated in the 
anal3'sis. 
The following are determinations of the phosphoric acid actually dissolved 
by water from guano, and, in comparison with them, I have put the results 
of the usual analysis : — 
No. 1. 
No. 2. 
No. 3. 
No. 4. 
No. 5. 
No. 6. 
Phosphoric Acid dissolved by'l 
Water ) 
As determined by the usuall 
Per cent. 
.3-10 
2-84 
Per cent. 
3- 08 
4- 6G 
Per cent. 
3-94 
3-81 
Per cent 
3'46 
3'4G 
Per cent. 
3 -.51 
4'17 
Per cent. 
1-16 
3-60 
In four out of six samples here given, the soluble phosphoric acid, as deter- 
mined by the usual analysis, closely accords with that which water actually 
dissolves from the guano. On the whole, therefore, we may with tolerable 
safety adopt the numbers given in the table as the " phosphoric acid in 
alkaline salts." 
XXVI. — On Afjriciiltural Statistics. By C. Wren Hoskyns, 
Wroxhall Abbey, Warwickshire. 
'Suppose a ship bound on a twelvemonth's voyage; that she 
cannot touch at any port short of her destination, nor by any skill 
of sailing shorten her passage by a day ; that the number of her 
crew and passengers is known, and even its variation by death or 
birth, during the trip, ascertained with tolerable precision : what 
would be tliought of the captain who should steer on his errand 
across the " trackless waste " without any knowledge of the 
quantity or kind of food on board — its proportion to the number 
to be supported, and the length of the voyage ? ' 
Such, in substance, is the illustrative yet simple shape in which 
a private gentleman, uncommissioned by authority, and not at all 
anticipating any after-publication of his words in a folio blue 
