THE ASH CONSTITUENTS OF PLANTS. 215 



Slater^ barium superoxid, Wackenroder^ lime, calcium carbonate, 

 and (.-alciuni acetate, all with good results. Von Schroder and Reuss* 

 in the analj'sis of forest products impregnated the substance with a 

 solution of sodium carbonate previous to charring, to prevent the loss 

 of chlorin and sulphuric acid. Councler* added to each gram of sub- 

 stance to be burned 1 cc. of a 10 per cent soda solution, dried, charred, 

 and incinerated over an alcohol lamp. Behaghel von Adlerscron and 

 Bunge'' earlier showed that in incinerating animal substances correct 

 figures for the chlorin content were obtained only with the addition of 

 sodium carbonate. 



Shuttle worth'' found the addition of a measured quantity of calcium 

 acetate of known calcium content very advantageous, the lime result- 

 ing from the higher heating retaining the chlorin and preventing the 

 fusing together of the salts, so that the mass remained porous and dif- 

 ticulth' decomposed silicates were not formed. This admixture is 

 especially to be recommended in case of substances like straw, which 

 are rich in silicic acid, with leaves, and with seeds rich in phosphoric acid. 

 With potatoes it is not necessary, as von Daszewski^ has found, because 

 they are easily and completely incinerated without such addition. 



A further advantage of the addition of alkaline substances in the 



incineration is the avoidance of the formation of pyro-phosphate in 



the ash and incomplete precipitation of the phosphoric acid, which 



may result in case of insufficient treatment of the ash solution with 



"nitric acid.* 



Addition of sulphuric acid in incineration. — In the analysis of 

 molasses and other sugar products, the incineration is now generally 

 carried on with the aid of sulphuric acid, as proposed b}^ Scheibler.® 

 This addition simplifies the operation very materially, but the bases 

 are naturally all recovered in the ash as sulphates. As this increases 

 the weight over the bases themselves or their carbonates, a correction 

 must be made in the weight of the sulphate ash, which according to 

 Scheibler should be about one-tenth of the ash. Although this factor 

 is now commonly used for the correction, it is onlj" a conventional 

 factor and by no means accurate under all circumstances. Hence, 

 others, as Biard,^** Sidersky, von Lippmann, and Wiechmann," have 



1 Jour. Prakt.-Chem., 65 (1855), p. 253; Chem. Gaz., 1855, Feb., No. 295, p. 53. 

 ''Arch. Pharm., 53 (1848), p. 1. 



^ Die Beschiidigung der Vegetation (lurch Eauch, p. 131. 

 ••Landw. Vers. Stat., 27 (1882), p. 375. 

 ^Ztschr. Analyt. Chem., 12 (1873), p. 390. 

 « Jour. Landw., 47 (1899), p. 173. 

 nbid.,48 (1900), p. 22.3. 



8Von Raumer, Ztschr. Analyt. Chem., 20 (1881), p. 376. 

 ^Ztschr. Ver. Riibenz. Zuckerind., 1864, p. 188; 1867, p. 338. 

 i"Ibid., 1891, p. 93. 

 "Ztschr. Analyt. Chem., 35 (1896), p. 699. 



