some varieiies of South American Guano. 137 



being obtained through different sources? Putting aside all 

 considerations of the mode of application to the soil, it is ob- 

 vious that the effects of such manures must vary almost as 

 widely as their composition ; and that whilst the employment 

 of such guano as No. 1, or even No. 2, would be in all pro- 

 bability attended with highly successful results, the use of the 

 others, or even of these mixed with several lumps of Nos. 5, 

 6 and 7, would, on the contrary, completely disappoint the 

 expectations of the agriculturist, and probably in some cases, 

 especially where such a kind as No. 7 exists in quantity, or 

 has deliquesced and been absorbed by the other portions of 

 the guano, its application would be attended with positive 

 injury. 



The analyses of the ordinary guano detailed in this paper 

 do not differ so considerably from Voelckel's analysis in com- 

 position, and the salts which they respectively contain, as to 

 render many observations on this the most complete analysis 

 I have met with necessary. In no one instance of the seven 

 specimens of guano examined by me could I detect carbonate 

 of ammonia in sufficient quantity to affect lime-water, although 

 in two cases out of the seven, nitrate of barytes indicated a 

 faint trace of this, substance. The solutions in cold water 

 were either neutral or slightly acid : these solutions di- 

 stilled afforded a solution which was distinctly alkaline to test- 

 paper, and contained a considerable quantity of ammonia, but 

 it was in an uncombined state, not as carbonate ; the resi- 

 dual solution in the retort subsequent to distillation was 

 markedly acid, so that this ammonia arose from the decom- 

 position of the phosphate of ammonia by boiling the solution 

 containing it. Some portions of guano, gently dried and 

 then sublimed, gave off ammoniacal fumes, and a white 

 sublimate from the oxalate, muriate and other ammonia salts, 

 but the sublimate contained no carbonate of ammonia. In 

 this respect my results differ from those of Girardin, Bidard 

 and some others,who describe carbonate of ammonia to exist in 

 considerable quantities in the South American guano analysed 

 by them. May they not have assumed that the ammonia libe- 

 rated by heat existed as carbonate, as I did myself until these 

 analyses obliged me experimentally to determine the question ? 

 Carbonate of ammonia is a substance, which, considering the 

 composition of guano, does not appear unlikely to be pro- 

 duced ; so that whilst I admit the possibility and even the 

 probability of its presence on these grounds, yet experiment 

 on seven distinct samples shows that it is absent. 



The existence of the free uric acid which separated from 

 the solution in boiling water of No. 1, maj' be questioned as 

 Phil. Mag. S. 3. Vol. 26. No. 1 7 1 . Feb. 1 84.5. L 



