PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 233 



The most conspicuous point is the general absence of effect 

 from muriate of potash. In only two cases does it raise the pro- 

 duce above that of the nothing plots. In most it is nearly the 

 same, and in one or two it is actually diminished. It is impos- 

 sible at the present moment to determine the cause of its effect 

 in the first two cases, but it seems very clear that the whole 

 balance of evidence is against the use of muriate of potash alone. 

 AYhen mixed with phosphates, also, its effect is generally un- 

 favourable, or at all events it is so uncertain that no reliance 

 can be placed upon it. But when both these substances are used 

 along with ammonia, the effect, though not invariable, is generally 

 very good, and some of the largest crops have been got in this way. 



This fact recalls to mind the results obtained last year by the 

 use of nitrogenous manures alone, which were so entirely nugatory 

 as to render it, in the opinion of the committee, unnecessary to 

 try them this year. It appears, indeed, very obvious that the 

 use of a single fertilising ingredient, alone, is rarely of much ser- 

 vice, and that in all cases the best effect is produced by the 

 mixture of several. It is no doubt for this reason that the farmer 

 generally obtains his best crops from mixtures of manures, the 

 one supplying what the other is deficient in. 



As regards the effect of nitrogenous manures in this year's ex- 

 periments, where they are used only with other substances, it is 

 in many cases insignificant, and the ready-formed ammonia 

 certainly does not surpass that existing in the form of glue. In 

 two sets of experiments, Peruvian guano, the most highly nitro- 

 genous mixture used, gives the best effect ; but in other instances 

 it does not stand so high, though it generally gives a good result. 



It is interesting to notice how greatly the productive capacity 

 of the soil has varied, as indicated by the produce of the nothing 

 plots, showing that soils of very different kinds, and in different 

 conditions, have been used for the experiments, and this, it is 

 scarcely necessary to say, is a most important feature in such 

 experiments, because it is only by this means, and by continuing 

 them until a sufficient number have accumulated, that we can 

 hope to trace out the influence which the character of the soil 

 has on the amount and quality of the crop. 



I refrain at the present time from discussing more at length 

 the minutiae of these experiments, lest I should be led farther 

 than facts warrant. I do not doubt that those who study them 

 carefully will find in them much that is of interest, and agree 

 with me in the opinion that the best thanks of the Society are 

 due to the gentlemen who have expended so much time and 

 labour and accuracy in conducting them. 



