/. D. Hague on the Guano Islands of the Pacific Ocean, 233 



sis of Jarvis guano in his "Eeport on the Guanos of Baker's 

 and Jarvis' Islands, Aug. 7th, 1860." 



The following presents some of the results obtained by these 

 two chemists : 



Lime 34-839 ' 34-79 



Phosphoric acid, 17-601 18-48 



In Johnson's samples nearly the whole of the phosp^horic acid 

 is combined with the lime as 2CaO, HO, PO^, while Liebig finds 

 for the above, 



2Cao,' Horpos',! !!] !!!!!.'"!".!'.! V. ".'.'.*.!! ! 16-026 " 



The formation of the neutral phosphate in this guano I think 

 may be considered as a result of the action of sea water to which 

 this part of the deposit has been subjected. It will be remem- 

 bered that in describing the Baker's Island deposit 1 gave an 

 analysis of a piece of crust found there, in which the phosphoric 

 acid was likewise partly combined as the neutral salt. In that 

 crust was also noticed a much larger percentage of sulphuric 

 acid than is found in the guano from which it was formed ; and, 

 further, it was observed that on Baker's Island this crust only 

 occurs in places of which the appearance and position indicate 

 that water (probably from high seas washing over the crown of 

 the beach) assisted at its formation. It seems to me probable, 

 ^nder these circumstances, that sulphates resulting from the 

 evaporation of the sea water have been decomposed, and that 

 the sulphuric acid has united with the lime of the bone phos- 

 phate, causing the formation of the di-phosphate of lime. 



That this process may have been carried on to a much greater 

 extent at Jarvis' Island, where much of the deposit has evidently 

 long been acted upon by sea water, seems to me beyond a doubt. 



A singular feature is presented by this crust m the formation 

 of so-called ' hummocks,' an idea of which may be better obtained 

 from the accompanying cuts than from words. These 'hummocks 



^ary in diameter from one to ten inches and m height from half 

 ;^ inch to six or seven inches. The exterior is composed of the 

 ,^,M phosphatic crust, while within each one, ^uthout except-.on, 

 Jere is a central mai of soft, amorphous and nearly pure hy- 

 •"ated sulphate of lime. When one of these is cut through ver- 

 ^ JOTO. Sci.-Seco>t> Sebie», Vol- XXXIV, No. 101--Sept„ 186S. 



