SUPERPHOSPHATE OF LIME. 1G7 



Sulphuric acid is preferaLle to muriatic acid, for several 

 reasons — it is strong-er, cheaper, has g'reater specific gn-avity, 

 and contains much less water. On mixing- it with water, a 

 much hig-her temperature is attained, which conduces to the 

 dissolving- process, particularly of the org-anic jiortion 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, however, been rather surprised 

 that there should not have been a more decided ditference 

 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 employed Avas one- 

 half, which was perhaps sufficient to affect all the phosphate 

 of lime contained in the bones ; whereas, if one-half had 

 been employed, as was tried Avith the sulphuric acid, the 

 result mig-ht not have been so favourable for the muriatic 

 acid. Besides this, probably the miu-iate of lime formed by 

 the muriatic acid is more fertilizing- and soluble than sul- 

 phate of lime formed by the srdphiu-ic acid ; and, from its 

 gTeat attraction for moisture, j^articularly advantag-eous ia 

 such a dry season as that of 184-i. It is, therefore, by no 

 means improbable that an equal qiumtity of bones, prepared 

 separately Avith the two acids, and afterwards mixed to- 

 g-ether, mig'ht be more productive than bones prepared with 

 either acid alone. 



The ])roportion of sulphuric acid most desirable to employ 

 is a very important })oint, inasmuch as it has been shown 

 that sulphuric acid alone, or mixed with Avater, possesses 

 very little fertilizing- poAvers. This, probably, is OAving* to 

 the circumstance of the soil g-enerally containing- a suffi- 

 ciency of this element, and to the fact that phos])horic acid 

 is so extremely essential, ])articularly in the earh' stag-es of 

 the g-roAvth of the plant, that it Avill not prosper Avithout it, 

 whatever Ave may otherAvise emplo}' as manure. A neig-li- 

 bouring- ag-riculturist, during- the last year, tried to raise a 

 crop of turnips with a good dressing- of salt and soot, which 

 contain no phosphoric acid, thoug-h plenty of ammonia and 

 other fertilizing- ing-redients, but the result Avas a total 

 failure. In a g-arden experiment, I may here observe, I 

 found sulplnu'ic acid and Avater succeed as Avell as bones in 

 raising' turnips, but the soil no doubt contained phosphoric 

 acid, as Avell as alkalies, on Avhich the acid could act fa- 

 vourably. 



Before Ave authoritatively pronounce on the quantity of 



