some varieties of South American Guano. 131 



acid and filtered ; in no one instance did any evolution of car- 

 bonic acid take place; the solution was then treated with am- 

 monia in excess, which precipitated the oxalate and subphos- 

 phate of lime, perhaps the magnesia also ; acetic acid was then 

 rapidly added until it was distinctly acid to litmus paper, and a 

 slight acidity could be detected by the taste ; the insoluble pre- 

 cipitate being collected, thoroughly washed, dried, and ignited 

 with the usual precaution, indicated the amount of the oxalate 

 of lime; this precipitate was invariably examined for phos- 

 phate of lime; if it contained any, this was separated in the 

 state of bone-phosphate and estimated as neutral phosphate, 

 in which state of combination it existed mixed with the oxa- 

 late of lime. 



To the acetic acid solution excess of oxalate of ammonia 

 was added, this precipitated the lime present in the solution ori- 

 ginally as bone-phosphate, sometimes mixed with neutral phos- 

 phate of lime, and from the weight of the resulting carbonate 

 of lime, and the loss of weight sustained by ignition of another 

 portion, correcting each other, the amount of the phosphate 

 of lime was calculated. The filtered solution evaporated until 

 a slight pellicle began to form, was treated with ammonia in 

 excess, and a little phosphate of soda, observing the usual pre- 

 cautions recommended by Berzelius, and the resulting ammo- 

 niacal phosphate of magnesia was collected and weighed. The 

 portion insoluble in hydrochloric acid being treated with potash 

 gave a solution possessing the properties described to belong 

 to an alkaline solution of the substance termed humus or 

 humic acid ; this was precipitated, collected and weighed ; the 

 residue insoluble in potash was weighed and ignited, the loss of 

 weight noted, and the product treated with hydrochloric acid ; 

 if effervescence ensued on this addition from the presence of 

 carbonate of lime, this was estimated as oxalate, and was added 

 to the amount already obtained of that salt; by these means 

 the proportion of the organic matter insoluble in potash, the 

 humus, oxalate of lime (if any), sand, &c. &c. undissolved by 

 hydrochloric acid, were obtained. 



The proportions in which these substances existed in the 

 guano were then ascertained by the necessary series of calcu- 

 lation. 



Where the proportions of acid and base, as ascertained by 

 analysis, did not exactly agree, the estimate derived from the 

 quantity of the acid was preferred, as being far less subject to 

 error than the process for estimating the respective amounts 

 of the potash and soda; the requisite loss or gain was always 

 placed to the soda, and this will account for the differences of 

 the losses sustained between the constituents of these samples 



