354 Transactions of the American Institute. 



Furthermore, as the constituents of p;uano are very sohible, and act 

 rapidly upon vegetation, it follows that their action is limited in 

 duration, and for this reason it is best to combine the use of guano 

 with barn-yard manure ; one-half the quantity of the latter combined 

 with an equivalent of guano being but a trifle less efHcient in imme- 

 diate effect than if guano alone wwe used, and at the same time 

 continuing to show results upon the crops for a longer period, Next 

 in importance to the guano, and much more artificial in their nature, 

 are the so-called poudrettes, made by combining the night-soil of 

 cities with materials capable of absorbing or neutralizing the ammonia 

 in or resulting therefrom. Like guano, these compounds vary greatly 

 in value, the difference arising from the greater or less degree to 

 which their ammonia has been fixed. They may be considered as 

 inferior to guano in the proportion of phosphatic matter, and may be 

 employed in the same manufir as the ammoniacal guano, care being 

 taken, as in the use of the latter, to apply the poudrette either just 

 before or during the rain, in order that its virtues may be carried into 

 the earth, and not dissipated in the air. With regard to the adul- 

 teration of both of these varieties of fertilizers, it may be said 

 that with guano the sophisticated article is so often made to resemble 

 the pure substance that an inexperienced person cannot be expected 

 to know the difference, and the fraud can only be detected b}^ an 

 analysis by a competent chemist. "With poudrette the very process of 

 manufacture affords opportunities for adulteration with infertilizing 

 materials, and the test just named is the only one that can be relied 

 upon as a true index of its value. In addition to the two varieties of 

 artificial ammoniated fertilizers which we have just considered, and 

 belonging to the same class therewith, may be named the products 

 resulting from the composting with other materials of the blood from 

 slaughter houses, the refuse hair from tanneries, and in general any 

 animal orjiitrogenized substances ; but the most notable example of 

 this class remaining for consideration is probably the so-called fislr 

 guano, which is simply the refuse or pomace left after the expression 

 of oil from the fish called moss bunkers, on the Atlantic coast. The 

 tissues of fish are believed to contain a larger proportion of phosphorus 

 than other flesh ; arid the presence of the fish bones in the material 

 just indicated, add an increased proportion of phosphoric acid, which, 

 with the ammonia resulting from the decomposition of the tissues, 

 must in the very nature of things constitute a very valuable manure, 

 j)rovided it is put into the market without adulteration. It is not, 



