/. D. Hague on the Guano Islands of the Pacific Ocean. 227 



observed scattered crystals of the phosphate of magnesia and 

 ammonia* It is closely though not hard packed, and i.s readily 

 removed by shovels without the aid of picks. la this part of 

 the deposit the portulacca flourishes most. 



The guano on the southern side is of reddish color, of finer 

 texture, much damper, and of less specific gravity than that just 

 described. There is much less vegetation in this part of the 

 deposit, and the guano here contains scarce any roots or fibres. 



Chemically these varieties do not differ very much. Usually 

 the darker sort contains less water and more organic (vegetable) 

 matter, from which it probably derives its color. 



Analyses of these two sorts are given beyond. 



Much light may be thrown on the formation of these deposite 

 by the analysis, (I) which follows, showing the composition of 

 recently deposited guano. The sample itself does not represent 

 any considerable part of the existing deposit, but was taken 

 from a locality where large numbers of birds are still accustomed 



3 congregate. It is the dung of the Pelicanus Aquilus, com- 



"lonly called the Frigate Bird, w' ' ' " '" ^'-' "-'-"- ''"^^ """ 



the island is the only one whose 



ily called the Frigate Bird, which of all the birds frequ 

 island is the only one whose recent evacuations are of sucn 

 consistency that they may conveniently be collected. I hey 

 contain a large proportion of solid matter, while the evacuations 

 of nearly all the other birds are very thin and watery. It is 

 found in their favorite roosting places, and shows the character 

 of guano before it has long been subjected to the influence of the 

 weather. It is a light and dry substance, consisting of friable 

 grains or fine powder, of a brown color, smelling strongly of 

 ammonia. Of the three following analyses No. I is this freshly 

 deposited guano; No. If is of the light colored guano from the 

 deeper part of the deposit, and No. Ill of the dark guano from 

 the shallow part. ^ „ m. 



Moisture expelled at 212° Fahr., ^040 2«2 





' • I contained S-82 per cent of actual ammonia and all con- 

 ieTof iron I al^o oSned in sample I. a strong reaction 



'^'^srmple (^^o. D resembles Peruvian Sf^^J^^^^^lJ^^n 

 jP-ts, and Us to L conclusion that tbedifl^^^^^^^^^ 

 •■oat and the American guano is mamiy owing 

 °i climate. 



♦ Liebig'a Report oa Baker and Jarris Qmxm Aug. ttb. I860. 



