146 
Superphosjyhate of Lime. 
of compost, I am in a position to state that by its means one-half 
the usual expense in the purchase of bones may be saved. 
We cannot, however, do better than take as our text, or rather 
the heads of our subject, the points to which the attention of com- 
petitors are drawn by the Council of the Royal Agricultural So- 
ciety, which are — 
1. State of Bones. 
2. Proportion of Acid in a given weight of Bones. 
3. Proportion of Water, if any, mixed with the Acid. 
4. Mode of mixing the Bones with the Acid, and of preparing 
the Compost. 
5. Effect of various quantities applied in combination or com- 
parison with common Bones and other known Manures. 
1. First, then, the state of the bones — with regard to which 
I have merely to observe that they should be as fine as possible, 
but the ordinary state of bone-dust will answer the purpose very 
well. The dust is decidedly preferable to half-inch bones, for 
whilst the increased weight of the former will compensate for its 
greater price, the points of contact being greatly increased by sub- 
division, the bones are more rapidly and more perfectly acted on 
by the acid, and require in fact a less quantity both of that and 
of water. 
We next come to the second and more important point. 
2. The proportion of sulphuric or muriatic acid to a given 
weight of bones. 
Sulphuric acid is preferable to muriatic acid for several reasons 
— it is stronger, cheaper, has greater specific gravity, and contains 
much less water. On mixing it with water a much higher tem- 
perature is attained, which conduces to the dissolving process, 
particularly of the organic portion of the bones. In addition to 
these reasons, we find that in the trials which have been made 
muriatic acid has been found somewhat inferior. I have, how- 
ever, been rather surprised that there should not have been 
a more decided difference than proved to be the case in Mr. 
Hannam's experiments ; and we can only account for this by 
bearing in mind that the lowest proportion of muriatic acid em- 
ployed was one-half, which was perhaps sufficient to affect all the 
phosphate of lime contained in the bones, whereas if one-third 
had been employed, as was tried with the sulphuric acid, the 
result might not have been so favourable for the muriatic acid. 
Besid(!S this, probably the muriate of lime formed by the muriatic 
acid is more fertilizing and soluble than sulphnte of lime formed 
by the sulphuric acid, and, from its great attraction for moisture, 
j)articularly advantageous in such a dry season as that of 1844. 
It is therefore by no means improbable that an equal quantity of 
