96 ANIMAL RESOURCES OF THE UNITED STATES. 



30. CHEMICAL PRODUCTS, &c — Continued. 



1c. 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. 



b. Artificial guanos: 



Menhaden guano. 

 Herring guano. 

 White-fisli 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. 



