NITROGENIZED PHOSPHATIC MANURES. 285 



treatment was applied to all guanos indifferently, so that for the 

 past fifteen years, 96 to 97 per cent of the dissolved guanos was 

 produced from non-deteriorated guano. In the later contracts 

 between the Peruvian Government and the Peruvian Guano Co., 

 this state of things has undergone no alteration. The process used 

 to dissolve Peruvian guano is as follows : — 



As the guano exists in big lumps in the raw state it must first 

 of all be ground to a fine powder. As it would be idle to pass all 

 the mass of guano through the crusher, the latter is combined with 

 a shaking sieve to separate the powder from the big lumps, which 

 are alone ground.^ The crusher also eliminates from the guano 

 stones (granite) 'brought from the deposits, which when they are not 

 too large are fixed between the bars of the machine, from which they 

 may be removed. In this way about 1 per cent of stones is ob- 

 tained, which is debited against the su^Dplies of the guano at the 

 purchase price. 



The powdered guano thus obtained is then mixed with 22 per 

 cent of its weight of sulphuric acid of 66° B., sp. gr. 1-84 (168° Tw.), 

 or with the equivalent of the acid at 60° B. As the phosphoric acid 

 exists as dibasic phosphate, the solution requires no plant, and is 

 done by simple shovelling. The material is then laid in heaps, 

 where it sohdifies. When the reaction is finished, the guano is 

 again passed through the crusher to reduce it to powder, the form 

 under which it is put on the market. Dissolved guano contains 

 5 to 7 per cent of nitrogen and about 10 per cent of soluble phos- 

 phoric acid ; it is sold with a guaranteed analysis. - 



As the Anglo-Continental Guano Co. can only supply a product 

 of uniform analysis, by carefully sorting and mixing the raw guanos 

 and not by the addition of foreign matters, sulphate of ammonia, 

 etc., it follows that the constant decrease in this nitrogen content 

 of the raw guanos reacts also on that of the dissolved guano. 

 Since 1878 the guano has been delivered uniformly with 10 per 

 cent of phosphoric acid and 5 to 7 per cent of nitrogen, at the wish 

 of the buyer. Dissolved guano has a considerable advantage over 

 raw guano — that of acting with absolute certainty. If the phos- 

 phoric acid of raw guano dissolve in the soil, when the temperature 

 conditions lend themselves thereto, it is precisely this subordination 

 which lessens its value and renders it illusory. As the solubility 



1 The author seems to the translator throughout the manufacturing section 

 to have recourse to the disintegrator a little too often when it seems possible less 

 drastic means would do. But here the author himself owns the futility of grind- 

 ing powder, but throughout the previous text he seems to recommend passing 

 everything through the disintegrator — the whole manure such as it is, not only 

 core but the friable portion as well and even loose friable superphosphate. — Te. 



- All manures in Great Britain must be so sold to meet the requirements of 

 the Fertilizers Act. — Tr. 



