750 GUANO 



6. The last liquor filtered, being freed from any residuary particles of lime by oxa- 

 1ate of ammonia, is evaporated to drynoss and ignited, to obtain the fixed alkaline 

 matter. This being weighed, is then dissolved in a little water, neutralised with acid, 

 and treated with soda-chloride of platinum. From the quantity of potash -chloride of 

 platinum, which precipitates, after being filtered, dried, and weighed, the amount of 

 potash present is deducted ; the rest is soda. These bases may be assigned to the 

 sulphuric, hydrochloric, and phosphoric acids, in proportions corresponding to their 

 respective affinities. 



7. The proportion of organic matter in the above solution of guano, is deter- 

 mined directly by evaporating a certain portion of it to dryuess, and igniting. Tho 

 loss of weight, minus the ammonia and oxalic acid, represents the amount of organic 

 matter. 



8. A second portion of a solution of tlie guano is evaporated to dryncss by a gentle 

 steam heat, weighed, inclosed in a stout well-closed phial along with alcohol of 0'825, 

 and heated to 212. After cooling, the alcoholic solution is decanted or filtered clear, 

 evaporated to dryness by a gentle heat, and weighed. This is urea, which may I": 

 tested by its conversion into carbonate of ammonia, when heated in a test-tube or small 

 retort. In this way I have obtained from Bolivian guano 5 per cent, of urea ; a certain 

 proof of its entire soundness. 



9. Analysis of the insoluble matter. One third of it is digested with heat in abun- 

 dance of borax- water, containing ^ of the salt, filtered, and the filter dried by a steam 

 heat. The loss of weight indicates the amount of uric acid, which is verified by super- 

 saturating the filtrate with acetic or hydrochloric acid, thus precipitating the uric acid, 

 throwing it upon a filter, drying, and weighing it. This weight should nearly agree 

 with the above loss of weight, the small difference being due to soluble organic matter, 

 sometimes called geine and nlmic acid. The uric acid is evidenced, 1, by its specific 

 gravity, which I find to bo only 1'25, as also that of the urate of ammonia ; 2, by its 

 affording fine purple murcxide when heated in a capsule along with nitric acid, and 

 then exposed to the vapour of ammonia from a feather held over it ; 3, by its dissipa- 

 tion when heated, without emitting an empyreumatic odour. 



10. Another third of the solid matter is distilled along with half its weight of slaked 

 lime, and 10 times its weight of water, in the apparatus already described, and the 

 ammonia obtained from it estimated. 



11. The remaining third having been ignited, is digested with a gentle heat in weak 

 hydrochloric acid, and the undissolved silica and alumina washed on a filter, dried, and 

 weighed. To the hydrochloric solution, dilute sulphuric acid is added, and the mixture 

 is heated till all the hydrochloric acid be expelled, with the greater part of the water. 

 Alcohol of 0'850 is now poured upon the pasty residuum, and the whole, after being 

 well stirred, is thrown upon a filter. The phosphoric acid passes through, as also the 

 magnesia in union with sulphuric acid. The sulphate of lime, which is quite insoluble 

 in spirits of wine, being washed with them, is dried, ignited, and weighed. From the 

 weight of sulphate of lime, the quantity of phosphate of that earth that was present 

 becomes known. 



12. Ammonia in excess is now added to the filtrate, which throws down the granular 

 phosphate of ammonia and magnesia. After washing and drying this powder at a 

 heat of 150, its weight denotes the quantity of that compound in the guano. 



13. To the filtered liquor (of 12), if a little ammonia be added, and then chloride 

 of magnesium be slowly dropped in, phosphate of ammonia and magnesia will pre- 

 cipitate, from the amount of which the quantity of phosphoric acid may be estimated. 



14. The proportion of oxalate of lime is determined by igniting the washed residuum 

 (of 9), and placing it in an apparatus for estimating the quantity of carbonic acid 

 given off in dissolving carbonate of lime. I have rarely obtained more than ^ gr. of 

 carbonic acid from the insoluble residuum of 100 gr. of good guano, and that corre- 

 sponds to less than 1 per cent, of oxalate of lime in the guano. Sometimes no 

 effervescence is at all to be perceived in treating the washed residuum with acid after 

 ignition. 



15. The carbonate of ammonia in guano is readily determined by filtering the solu- 

 tion of it in cold water, and neutralising the ammonia with a test or alkalimotrical acid. 



16. Besides the above series of operations, the following researches must be inado 

 to complete our knowledge of guano. The insoluble residuum (of 10), which has 

 been deprived by two successive operations of its uric acid and ammonia, may 

 contain azotised organic matter. It is to bo therefore well dried, mixed with f> times 

 its weight of the usual mixture of hydrate of soda and quicklime, and subjected to 

 gentle ignition in a glass or iron tube closed at one end. and connected at the other 

 with an ammonia-condensing apparatus. The amount of ammonia, bein^ est i mated by 

 a proper ammonia-meter, represents the quantity of azote, allowing 14 of this element 

 for 17 of ammonia, being the potential ammonia corresponding to the undefined 



