ORGANIC NITROGEN FERTILIZERS 113 



of a balloon, whereby the dust and air are blown into a 

 large canvas bag, all the air having to pass through the 

 canvas, and leaving the fine dust behind. (Fig. 4.) By 

 tapping the bag, the 

 accumulated dust can be 

 shaken out at the bottom. 

 This not merely removes 

 the nuisance, but obtains 

 some very valuable ma- 

 terial, the dust being some 

 of the richest fractions. 

 The fish manure produced 

 by these methods con- 

 tains about 8 % of nitro- 

 gen, 6 % ot phosphoric 

 acid and i % of potash. 

 Other methods of utilizing 

 the fish refuse have also 

 been employed from time 

 to time. According to 

 other methods the fish is 

 boiled, and the fish 're- 

 fuse pressed, this process 

 closely resembling that of 

 the seed oil process. 

 Without boiling the fish A 

 it could be neither ex- B 

 tracted nor pressed with 

 any success. Boiling me- 

 thods usually produce a 

 different quality of ma- 

 terial to that obtained by 

 the extraction methods. 



FIG. 4. Dust-catching balloon. 



is the intake of dusty air blown by 

 some fan. 



is the balloon into which all the dusty 

 air is forced, and through the pores 

 of which the air escapes, the dust 

 being thus filtered out. 



is the exit pipe of the balloon, which 

 is tied by a cord until the balloon has 

 accumulated sufficient dust. The 

 balloon is then beaten till the dust 

 falls down into the exit tube (C), the 

 cord is released, and the material is 

 allowed to be blown into a sack. 



Some varieties of fish 

 contain far more phosphate 

 nitrogen than others. Refuse 



and correspondingly less 

 from the Newfoundland 



cod fishing contains about 5 % of nitrogen and 40 % of 

 phosphates, owing to the large amount of bone contained in 

 v. 8 



