I. AGRICULTURE AND RURAL ECONOMY. 395 



while, if facing the direction of the wind, the air will be blown 

 through the tube into the grain. In this way the air, instead 

 of remaining in the interstices of the grain and becoming sat- 

 urated with moisture, causing a tendency to mildew or dust- 

 iness, will be continually changed. It is asserted that the 

 trial of the apparatus has proved very satisfactory in its re r 

 suits. SA, May 1,1872, 72. 



COMPARATIVE VALUE OF DIFFERENT GUANOS. 



As the deposit of guano upon the Chincha Islands is nearly 

 exhausted, the importance of other nitrogenous fertilizers 

 now in the market has greatly increased. A number of prom- 

 inent German chemists have analyzed several of these, and 

 we give in the following summary some of the results ob- 

 tained by them. Guanape guano is found in the rainless 

 region of Western South America, along the coast of Peru. 

 Its composition is very variable, but it is recommended as a 

 fit material for the manufacture of superphosphates to secure 

 a more uniform action. Saldanha Bay guano, from the 

 Western coast of Africa, contains more than 27 per cent. of. 

 insoluble mineral ingredients. Whale guano, from Norway, 

 contains 3.6 per cent, of nitrogen and 17.0 of phosphoric acid, 

 and is a very rapid fertilizer. The gelatinous matter, con- 

 taining over 8 per cent, of nitrogen and 3 per cent, of phos- 

 phoric acid, is also sold for the same purpose. The produc- 

 tion of the Norwegian fish guano, mainly from the offal of 

 codfish at the Loffoden Island, is constantly increasing. Mai- 

 den and Starbuck guano, both from the group of Phoenix Isl- 

 ands, in the Pacific, and the Mejillones guano, from Mejillones 

 Bay, on the boundary of Bolivia and Chile, as also the Baker 

 guano, and perhaps the Sombrero and other West Indian 

 guano, are varieties which have lost nearly all their nitrogen 

 by the influence of rain, but are extremely rich in phosphoric 

 acid, and thus especially adapted for the manufacture of 

 highly- concentrated superphosphates. In one sample of 

 Mejillones guano there were found 1 per cent, of nitrogen 

 and 75 per cent, of phosphoric acid. Maiden guano contains a 

 considerable quantity of alkaline carbonates. The Ba Plata, 

 or Carno guano, is made from the residuum left in the prep- 

 aration of. the South American meat extract. 



In Austria a fertilizer has lately been introduced by the 



