I. AGRICULTURE AND RURAL ECONOMY. 385 



verse variation of nitrogen, compared with that of the phos- 

 phates, indicates that the sample in one case was made al- 

 most exclusively of the flesh, while in the other case it in- 

 cluded also a large amount of bones. Analyses of the so- 

 called Norway fish-guano, which first appeared in the Ger- 

 man market in 1862, also show great variations in the per- 

 centage of phosphoric acid, doubtless due to the same causes. 

 Although fish are very prone to putrefaction, still many of 

 the fish-guanos decompose with difficulty in contact with 

 water. The remarkable resistance to putrefaction of some 

 samples was doubtless due to the presence of a large amount 

 of fat, which caused them to be moistened with difficulty, 

 and consequently to absorb water very slowly. The pres- 

 ence of such an amount of fat may have been the cause, in 

 many cases, of the unsatisfactory results of experiments with 

 fish-guano as a fertilizer, and may explain why its action 

 was not as rapid and evident as that of bird-guano. Re- 

 cently, however, this obstacle to the rapid and certain effect 

 of fish-guano has been removed by Radde, of Hamburg, by 

 the manufacture of so-called fatless, evaporated, polar fish- 

 guano, in which a minimum of 8 per cent, of non- volatile 

 nitrogen, and of 12 per cent, of phosphoric acid is guaran- 

 teed, and actual analysis of a sample gave a considerable ex- 

 cess above this minimum. This article is in the form of a 

 fine, dry powder, of yellowish color, with a comparatively 

 feeble odor. It absorbs water rapidly, and when moist pu- 

 trefies readily at 52, with copious formation of ammonia. 

 It yields on ignition 37 to 33 per cent, of ash. The phos- 

 phoric acid is present as a tribasic phosphate, and the nitro- 

 gen in non-volatile combinations, from which ammonia is 

 only liberated, as they decompose in the soil, thus affording 

 a rich continuous source of nitrogen to the plants, in which 

 particular it surpasses bird-guano. As a solid manure it 

 can replace any artificial manure ; in some cases, however, 

 potash should be applied with it in the form of wood-ashes. 

 As a liquid manure its value is indicated by the fact that 

 33 to 34 per cent, of it passes into a solution in cold water, 

 which, on evaporation, affords a residue, which contains, 

 when dried at 212, in addition to the soluble phosphates, 

 15 per cent, of nitrogen. In the liquid form it has been 

 found excellent for vegetables, fruit, and pot-plants. Ex- 



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