196 Composition and Value of Guano. 



XL — On the Comjwsition and Mtneij Value of the different 

 Varieties of Guano. By J. Thomas Way, Consulting- Chemist 

 to the Roval Agricultural Society. 



Time, which brings change to everv thing, has not been idle 

 with agriculture. Every year ushers in some novelty, if not im- 

 provement, in the shape of new implements, new plants for culti- 

 vation, and new manures. Not the least remarkable of these 

 introductions in modern times is that oi guano. The farmer who 

 employs, it may be, a few cwts. of this manure in the year, hardly 

 troubles himself to inquire the amount which is annually imported 

 into England, the distance which it is brought, and the capital 

 which is employed in its transmission. In one year between 

 three and four hundred thousand tons of all varieties are said to 

 have been imported ; and at the present time the yearly con- 

 sumption in this country alone of Peruvian guano does not fall 

 short of 80,000 or 100,000 tons. What then is guano? and to what 

 does it owe that undeniable fertilizing power which can repay 

 the cost of bringing it so many thousand miles across the seas ? 



It does not come within the scope of the present article to 

 offer a history of guano, or to recount the w^onders which it has 

 effected in the production of all kinds of crops. The reader may 

 refer to Professor Johnstone's paper on guano in this Journal 

 (vol. ii. pt. iii.) for a very interesting account of this singular 

 substance ; and if he requires any evidence of its value as manure, 

 he will find such distributed through any and every agricultural 

 publication of the last eight years. 



It will also occur to him that it has not been left to the present 

 time or to the present writer to place before the public as a 

 novelty the analysis of guano ; on tlie contrary, many very careful 

 and elaborate analyses have been undertaken for the purpose of 

 indicating the true composition of the different varieties, and, as 

 it is of a highly complex nature, analytical skdl of no ordinary 

 kind has been brought to bear upon its examination. Baron 

 Liebig has collected in an appendix to his fourth edition of ' The 

 Chemistry of Agriculture' very many of the analyses of guano which 

 had been published up to the date of that work, and as they com- 

 prehend pretty nearly all that is known of its composition, the 

 reader may be referred to the book in question for this information. 



These analyses however, highly valuable as they undoubtedly 

 are in a scientific point of view, are too much complicated by the 

 minuteness of their details to convey to the mind any definite 

 notion of the precise manurial value of guano, still less are they 

 applicable to calculations having in view the comparison of the 

 different varieties, in an agricultural sense, or the determination 

 of their average money value in relation to other recognised 

 manures, 



