96 ANIMAL EESOURCES OF THE UNITED STATES. 



30. CHEMICAL PEODUCTS, &c —Continued. 



k. Derived from protozoans : 



Burnt sponge, formerly used in medicine. 



Infusorial earth, and its applications. (See above, under K.) 



31. FERTILIZERS. 



a. Natural guanos : 



Bat guano from caves. 



Bird guano from oceanic islands, 

 1). Artificial guanos : 



Menhaden guano. 



Herring guano. 



White-fish guano. 



Other fish guano. 

 c. Artificial fertilizers: 



Bone-dust ground for use. 



Bone phosphates. 



Dried meat from refuse of slaughter-houses. 



Poudrettes. 



Other animal fertilizers. 



32. LIMES. (See under 30.) 



33. OTHER MATERIALS NOT MENTIONED. 



