GUARANTEED GUANO. 265 



" Lastly, the system of selling this fertilizer according to analysis, so 

 strongly advocated by scientific agriculturists, is here carried out in the 

 most complete manner. In purchasing ' Guaranteed Guano,' the farmer 

 will for the first time, as in the ' Rectified Peruvian Guano,' know pre- 

 cisely what he buys and exactly what he pays for it. 



" It is neither intended, nor can it be expected from what precedes, that 

 all guaranteed guano shall be of the same grade ; that is to say, shall 

 show the same analysis. But a cargo being thoroughly mixed and sam- 

 ples from it analyzed, the lowest analysis obtained will be the one adopted 

 for stamping on the bags ; so that the contents of each bag are guaranteed 

 to analyze as well, if not better, than marked upon it. No range, no 

 margin is in this respect claimed in favor of the seller. 



" Should any one wish to convince himself how cheap the fertilizing 

 ingredients are sold in the guaranteed guano without consulting the 

 tables formed for this purpose, let him take any of the good brands of 

 fertilizers and ascertain its analysis. Now, to estimate what such a 

 fertilizer would be worth, at the rates at which the same kind and 

 quantity of plant-food would cost in guaranteed Peruvian guano, proceed 

 in the following manner : — 



" Multiply each unit, or the percentage of ammonia in the fertilizer by 

 $3.50 (or if instead of ammonia the percentage of nitrogen be given, 

 allow $4.25 per unit). Multiply the percentage of soluble phosphoric 

 acid by $2 ; multiply the percentage of reverted phosphoric acid by $1.60 

 and the percentage of insoluble phosphoric acid by forty cents ; for potas- 

 sium oxide, if any, multiply the percentage by $1.50. Add together these 

 products, and the sum will be the value of the fertilizer at the rate that the 

 same ingredients can be purchased in Peruvian guano guaranteed. 



" Now, if the value of the fertilizer in question, according to the above 

 rule, be less than its retail price, the difference between the two will show 

 how much dearer per ton the fertilizer is than the same quantity of plant- 

 food in Peruvian guano guaranteed. If, on the contrary, the estimated 

 value of the fertilizer were greater than its retail price, the difference 

 would show by how much a ton of the fertilizer would be cheaper than 

 the same amount of plant-food in the guano. 



" Particular attention is called to the fact that the guaranteed guano 

 undergoes no other preparation but such as the raiv article would receive 

 from the farmer himself, previous to applying it to the soil ; viz., taking 

 out stones, if any, and crushing the lumps ; but this being done by 

 machinery, it is much more effectually accomplished than could be 

 performed on a farm, and it enables the sellers to offer the article in 

 unobjectionable condition, and to guarantee the analysis of each bag. 

 Furthermore, in order to prevent, if possible, the adulteration of guano, — 

 a practice which has, unfortunately, been carried on to some extent, — the 

 twine with which the mouth of the bag is sewn will have a lead seal 

 attached to each extremity, so that if the bags be tampered with it may be 

 easily detected. 



"Thus every means has been adopted and every precaution taken to 

 satisfy the legitimate expectations and pi-otect the interest of farmers 

 who employ Peruvian guano as a fertilizer. 

 34 



