48 MODERN HIGH FARMING. 



itics being of opinion that it must necessarily be before the deluge. 



In his very able book upon the subject, Mr. F. de Rivero ad- 

 vances some skilful arguments to prove that they are of more 

 recent date ; and, basing his calculations upon the existing quantity 

 of about 20,000,000 tons, he says : 



"Presuming the constant presence of only 264,000 of these birds, 

 (and I am perfectly convinced there is nothing at all exaggerated in 

 these figures), supposing each bird to furnish but one ounce of ma- 

 nure in every twenty-four hours, we easily arrive at the figure named, 

 in a period of between five and six thousand years." 



The value of real guanos from all sources is estimated upon the 

 basis of their nitrogen, ammonia, phosphate and organic matter, 

 and when of sound quality they have generally realized from $65 to 

 $70 per ton. 



The following are the analyses of two cargoes purporting to be 

 of the same quality and shipped from the same port at the same 

 time, arriving in London at the commencement of 1882 : 



PERUVIAN GUANO. 



CAUGO No. 1. CARGO No. 2. 

 Moisture 1G..OO 15.28 



"Organic Matter, ( ro , n 14 72 



Salt* of Ammonia )" ~ 50 14 ' <<J 



Phosphate of Lime 19 52 33.12 



tPhosphoric Acid 3.12 traces 



Alkaline Salts 8.00 8.93 



Insoluble and Sandy Matters 0.80 27.95 



100.00 100.00 



*Nitrogen 15 30 2.70 



tSoluble Phosphate of Lime 6.76 none 



As these are far from being exceptional instances of the great 

 uncertainly of these products, we feel compelled while admitting 

 that no better manure than good guano is to be found to advise the 

 discontinuance of their use, and the employment of well-made 

 chemical substitutes, until shippers guarantee them to contain a 

 stipulated minimum percentage of the active principles. 



