EEAL FISH GUANO. 317 



the season ; and the means, which are at present usually 

 employed to meet this difficulty, are, quite frequently, inade- 

 quate to the demand. Many manufacturers of fish oil con- 

 sider it, therefore, apparently a safer proceeding to dispose at 

 once of their crude stock at low rates, than to run the risk 

 any longer. Without questioning the soundness of their 

 course of action, in case of limited pecuniary means, there 

 seems to be no valid reason why improvements should cease 

 here as long as it is daily demonstrated that it pays well to 

 collect animal refuse matters from all over the country and to 

 work them into valuable concentrated fertilizers. 



Nobody familiar with the nature of a good fish guano con- 

 siders it less efficient for agricultural purposes, than any other 

 animal refuse matter of a corresponding percentage of phos- 

 phoric acid and nitrogen. In fiict, all true guanos, the Peru- 

 vian not excepted, owe their most valuable constituents, in a 

 controlling degree, directly or indirectly to the fish. 



Our fish guano consists of the entire bodj'^ of the man- 

 haden fish, which has been deprived purposely, of its main 

 portion of fat, and incidently, more or less completely of its 

 soluble nitrogenous matter. The more the flesh predominates, 

 the more the fat has been abstracted without the application 

 of an excessive heat, as far as time and degree are concerned, 

 the higher will be the commercial value of the residue of the 

 press in case of an equal percentage of moisture. The flesh 

 of the fish, like that of our domesticated animals, contains on 

 an average 15 per cent, of nitrogen. The same close approx- 

 imate relation exists between the bones and the textures of 

 these otherwise widely dijffering classes of animals ; for the 

 fish-bones and the scales consist, mainly, of a varying quantity 

 of cartilaginous (nitrogenous) matter and of (tricalcic phos- 

 phate) bone phosphate. 



To produce a fish guano which contains in a given quantity 

 the largest possible amount of nitrogen, must be the principal 

 aim of the manufiicturer. It brings the highest pecuniary 

 compensation ; for one percentage of nitrogen is commercially 

 equal to four per cent, of phosphoric acid. 



During the past, it is true, there has been little inducement 

 for considerations of this kind on the part of the manufact- 

 urer, because practically there has been scarcely any serious 



