On Siiperphosphafe of Lime. 



205 



sumed by our farmers is very great. Ten years have not yet 

 elapsed since this manure was first offered to the agricultural 

 public, but a sufficient amount of success has attended its use to 

 justify us in predicting that in a few years more superphosphate 

 of lime, or something of the same nature, will become an article 

 of general agricultural interest and importance. 



In relation to both of these manures the question then naturally 

 arises. What are they? What is or should be their composition 

 in a state of perfection? How nearly does their <2c^w<2/ condition 

 approach to what it should be ? And what is the average quality 

 which the consumer has a right to look for in purchasing 

 them ? 



It is known to the readers of the Journal that I have already 

 published a paper on the subject of guano in a former Number 

 (vol. X. part 1). In common v/ith many others, I had frequently 

 experienced the difficulty arising from having no standard to 

 which the composition and consequent money value of any par- 

 ticular sample of guano could be referred. The differences 

 between genuine samples of this manure were ahvays understood 

 to be very great, and it was next to impossible to say whether a 

 manifest inferiority in any particular specimen was to be held to 

 be accidental and due to some peculiarity in the formation of the 

 deposit, or, on the other hand, to be considered as the result of 

 fraud and adulteration. The examination of fully fifty samples 

 of the most important variety, the Peruvian, collected during two 

 years, sufficiently established the fact, that throughout that period 

 the composition of the genuine importations varied only within 

 very narrow limits. These limits being once defined, and the 

 average character of guano determined, we possessed henceforth 

 a standard of comparison to which we might confidently appeal 

 in all cases of difficulty. 



In the two years which have elapsed since those analyses were 

 published, I have examined a further very large number of 

 samples of guano, both from the cargoes as they reached this 

 country, and from quantities which, in the regular way of trade, 

 had passed into the hands of different consumers. Many of the 

 latter have turned out, on the most conclusive evidence, to be 

 grievously adulterated. Some few have been found to be 

 naturally inferior, but by far the greater number have possessed 

 the composition fixed by previous analysis as the average of the 

 genuine manure. 



Although, therefore, samples of guano may occasionally be 

 met with that, without any adulteration, have an inferior composi- 

 tion and a correspondingly less value than the genuine importa- 

 tions, there is no doubt that these cases are rare, and that the 

 purchaser of the manure has a right to expect that it shall come 



