20S 



Analyses of Ashes of Plants. 



for chlorine ; the excess of silver removed by hydrochloric acid ; sul- 

 phuric acid thrown down by chloride of barium. 



15 or 20 grains analysed for carbonic acid in the usual apparatus. 



If the ash be silicious, or contain much charcoal — 40 or 50 grains of 

 ash mixed with its own weight of finely powdered pure and dry nitrate 

 of barytes ; mixture thrown by platin\im-knife by small portions into 

 large platinum crucible gently heated by a spirit-lamp ; gentle deflagra- 

 tion occurs without loss ; ash becomes quite white, and easily decom- 

 posed by acids; treated with hydrochloric acid, evaporated to dryness, 

 the silica separated as usual. Correction made for sulphate of barytes 

 present; silica dissolved by boiling for half an hour with caustic potash, 

 filtered ; loss of weight ascertained. Sihca again separated by acid and 

 evaporation. A certain measure of the liquid precipitated successively 

 by caustic, barytes, and carbonate of ammonia, with caustic ammonia — 

 evaporated to dryness, residue ignited, weighed, dissolved in little water 

 and treated with chloride of platinum and liquid evaporated to dryness 

 in water-bath ; alcohol (containing a little ether) added ; salt collected, 

 washed with same liquid — dried at 212°. 



The remainder of the liquid precipitated by slight excess of dilute 

 sulphuric acid ; sulphate of barytes collected and weighed ; it always 

 contains some sulphate of lime, which admits of calculation from the 

 quantity of nitrate of barytes employed. One portion of the filtered 

 liquid nearly neutralized by ammonia — ^acetate of ammonia added — 

 warmed, and the phosphate of iron collected. Lime precipitated by 

 neutral oxalate of ammonia ; magnesia by phosphate of soda and am- 

 monia; to the lime is to be added that present in the sulphate of 

 barytes. 



A second portion of the liquid filtered from the sulphate of barytes 

 nearly neutralized by ammonia; acetate of ammonia and free acetic 

 acid added ; a solution of perchloride of iron of known strength added 

 from a delicate alkalimeter till the liquid is decidedly red — boiled till 

 the precipitate has separated, filtered ; ammonia added to the filtered 

 liquid will throw down phosphate of lime if phosphoric acid has escaped 

 (in which case more iron must be added), or peroxide of iron with a little 

 phosphate of iron, if iron has come through. This latter, which is 

 always small in quantity, must be collected on a separate filter ; but nei- 

 ther occurrence need be feared, if there be not too great an excess of 

 iron, if plenty of acetate of ammonia is used and the solution be well 

 boiled. The peroxide of iron present in the ash, and that added, being 

 deducted from the whole weight of the precipitate, the phosphoric acid 

 is the remainder. 



With ashes containing but little silica or charcoal the same method 

 adopted, but without deflagration by nitrate of barytes. 



(This method of burning and of analyzing the ash gives accu- 

 rate results. We have made a series of experiments upon the 

 liability to loss either in burning or in the subsequent analysis, 

 and the results are perfectly satisfactory — they will shortly be 

 published through some chemical medium.) 



