386 Chemical Society, 



The undissolved substance appeared to be a mixture of uric acid, 

 earthy phosphates, and brown organic matter. 



Fifty grains of guano by incineration in a platinum vessel left 16*9 

 grs. fine greyish white-ash. This ash, treated with hot water, and 

 the whole placed on a filter, left a quantity of insoluble matter, 

 weighing, after being well washed, dried and ignited, 14*6 grs. : 

 this was almost entirely soluble in warm dilute hydrochloric acid, 

 precipitated by the addition of ammonia, and evidently consisted of 

 phosphates of lime and magnesia. 



The aqueous solution was slightly alkaline, contained much chlo- 

 ride, some sulphate, a very notable quantity of soluble phosphate, 

 some potash, and a good deal of soda. 



Hence the following approximate result :< — 

 Oxalate of ammonia with trace of carbonate, 



undecomposed uric acid, brown organic mat- ^ 33' 1 66*2 



ter and water 



Earthy phosphates, with very little sandy matter 

 Alkaline phosphate and chloride with little"! 



sulphate J 



'7 



No. 2. — Darker in colour, and having but little smell, 

 as in preceding case ; it contained no uric acid. 



Fifty grains gave — 

 Oxalate of ammonia, with little carbonate, or- \ 



ganic matter and water / 



Earthy phosphates, with little gritty matter . . 

 Alkaline sulphates, chlorides and phosphates, T 



(both potash and soda, the latter most abun- > 



dant) J 



50- 100- 



The last specimen is evidently older and in a more advanced state 

 of decomposition than the other ; its odour is far less powerful and 

 offensive ; it contains little or no uric acid, but a larger proportion 

 of inorganic substances*. 



It is difficult to imagine a manure better fitted for almost uni- 

 versal use than this " guano ; " it contains in a highly concentrated 

 form everything that plants require for their sustenance, with the 

 exception perhaps of potash, which however is often abundantly 

 supplied by a soil poor in other respects. 



The presence of a large quantity of oxalate of ammonia is a cu- 

 rious fact, and was early noticed ; there can be no doubt that this 

 substance owes its existence in some way or other to the uric acid 

 contained in the excrement of the sea-birds, to the decomposition of 

 which the guano-deposits are due. We can easily imagine that in 

 this mass of putrefying substance, kept in a moistened state by the 

 dews of night, a decomposition of a peculiar kind may be set up in 

 the uric acid, and its gradual conversion into new products, among 



[* On the composition of guano, see also Phil. Mag., S. 3. vol. xix. p. 49.] 



