314 Notice of Guano from the Yorkshire Coasts 



per cwt. ; and has been used, from time immemorial, as a 

 manure for grain crops, in the proportion of about six cwt. 

 per acre, and with such effect, that it is held in great estima- 

 tion for its fertilizing power. 



It is of a light brown colour — a mixture of fine powder, bits 

 of straw and chaff, and a little sand and gravel. It has a pe- 

 culiar smell, but not ammoniacal till moistened and mixed 

 with lime, when it emits this odour distinctly. From a coarse 

 analysis of it which I have made, it appears to consist of — 



10 Saline matter, soluble in water, in which the muriatic, sulphuric, 

 and nitric acids were detected, with lime, potash, ammonia, 

 and magnesia. 



24 Organic matter, chiefly vegetable, destructible by fire, not soluble 

 in water. 



60 Matter not destructible by fire, of which 21 were soluble in muriatic 

 acid, consisting chiefly of phosphate of lime, with a little car- 

 bonate of lime and magnesia ; and 39 were insoluble, composed 

 principally of siliceous sand and gravel. 

 6 Hygrometric or adhering moisture. 



IGO 



This composition of the Yorkshire guano accounts, in a sa- 

 tisfactory manner, for its fertlHzing effect, especially when 

 applied to grain crops. 



It may appear singular, that, whilst mention is made of 

 nitric acid and soluble salts, as present in this guano, no notice 

 is taken of lithic acid, of which, in combination with ammonia, 

 as is well known, the urinary portion of the excrement of 

 birds chiefly consists. It was sought for, but in vain ; or, at 

 farthest, only an obscure trace of it could be detected. This 

 is not difficult of explanation, remembering that the lithate of 

 ammonia is soluble in water, and that the guano examined 

 had been exposed to the action of rain. In another specimen, 

 collected, at my desire, from parts of the cliff protected from 

 the weather, and for which, also, I am indebted to Mr Hodg- 

 son, I found a considerable quantity of lithate of ammonia. 



The nitric acid present — probably in combination with 

 lime— it may be conjectured, was derived, with the soluble 

 salts, from an overhanging surface of limestone rock, and was 

 either scraped off in gathering the excrement, or was washed 

 down by the dropping of water, and absorbed and retained by 



