10 VOELCKER on the Value of Artificial Manures. 



occasionally is attended with an abundant crop ; and as the 

 dealer or manufacturer takes good care to select for publication 

 only those opinions which are favourable to the sale of the manu- 

 factured article, and does not tell us how many expressions of 

 opinion he has received, which, when published, would damage 

 his business, it is evident that little dependence can be placed on 

 printed testimonials. 



It now remains for us to substantiate the truth of the assertions 

 contained in the above pages by some instances which have lately 

 come under our notice. 



Peruvian Guano. During the last season we have met not 

 only with several samples of guano of inferior qualities, sold as 

 the best Peruvian, but also with an instance of gross fraud. In 

 order to enable the reader to form a just estimate of the difference 

 between good and inferior guano, we will state the result of a 

 few analyses of good Peruvian guano : 



Composition of good Peruvian Guano. 



Water 



Organic matter and ammoniacal 

 salts* 



Phosphates of lime and mag- 

 nesia (bone-earth) 



Alkaline salts, chiefly chlorides 

 of potassium and sodium . . 



Insoluble silicious matter 

 (sand) .. 



*Yielding ammonia 



I. 



12-420 



52-980 



25-065 



8-262 



1-507 



100-236 

 17-215 



II. 

 12-00 



59-11 



19-31 



8-13 



1-45 



100-00 

 19-30 



III. 

 17-40 



49-97 



23-66 



7-43 



1-54 



100-00 

 18-96 



These are excellent guanos, and yield more than the average 

 proportion of ammonia which may be fairly expected in good 

 Peruvian guano, the average being 16 per cent. 



The following two analyses exhibit the composition of two 

 inferior samples of guano : 



Composition of two inferior Guanos. 



I. 



Water 11-32 



Organic matter and ammoniacal salts* .. 53*94 



Phosphates of lime and magnesia (bone- 

 earth) 30-98 



Alkaline salts, chiefly chlorides of potassium 



and sodium 6*62 



Gypsum 



Insoluble silicious matter (sand) .. .. 14'50 



* Yielding ammonia .. 



100-36 

 11-80 



II. 



11-54 

 19-79 



42-93 



14-78 

 1-70 

 9-36 



100-00 

 4-35 



