ZOOLOGY. 359 



possesses, however, a high value in special applications, and presents some 

 interesting scientific points. 



Dr. A. A. Hayes, of Boston, has fully investigated the composition of 

 the guanos of different islands, including ancient as well as recent deposits. 

 On some of these, two species of birds are still found, in countless num- 

 bers, which make daily additions to the accumulated remains of former 

 years. 



The substance of this kind of guano is matter derived from the fish food 

 of birds. Its color is light yellowish brown, becoming, when air dried, 

 nearly white. It has no ammoniacal odor, but smells strongly of freshly- 

 disturbed earth. It is never so finely divided as the Peruvian, its particles 

 being sometimes as coarse as mustard seed, resembling closely the sand 

 from Oolite limestone. There is, however, always some finely-divided or- 

 ganic matter, in the slate of humus, either between the particles, or making 

 part of the substance of them. An average composition is the following : 



Moisture, after being air dried, 4.40 



Organic matter, crenates, humates, oleates and stearates, 



magnesia and lime, 6.40 



Bone phosphate of lime, 46.60 



Carbonate of lime, 39.80 



Phosphate magnesia, . . . . . . . 1.20 



Sulphate lime, ........ .80 



Sand, .*...,.... .21 



Traces of chloride and sulphate of soda, 



99.41 



Tne carbonate of lime here given is an essential part of each particle of 

 the bone remains, and does not exist excepting occasionally as mixture, 

 to the amount of one or two per cents independently. The humic acid 

 is often in union with ammonia and magnesia, the whole percentage of 

 ammonia, or rather nitrogen, not exceeding in the ancient deposits more 

 than two per cent. A more solid aggregate of grains afforded : 



Moisture from air dried state, . . . . .. 5.40 



Organic matter, humates, humus, .... 



Oleates and stearates 8.40 



Bone phosphate lime, 64.80 



Carbonate of lime, 16.20 



Sulphate, 2.80 



Phosphate magnesia, . . . . . . . " 1.60 



Sand, .46 



99.66 



The grains adhered slightly ; the dry mass was of a pale nankin color, 

 and exhibited the first step in a change, which results in a consolidation 

 of the arenaceous remains into a solid rock. 



