14 



Page 79, section "7. Determination of chlorin" is to be omitted 

 until a more exact method can be offered (refers to chlorin in the 

 plant, according to new name of section, not to chlorin in ash). 



Page 79, add the determination of potash by ignition of the plant 

 substance with sulphuric acid, as described in the determination of 

 potash in fertilizers [p. 22, (3) Determination, (a) In mixed fertilizers,] 

 as an alternative method. 



The entire methods for the analysis of ashes as rewritten by the 

 referee were adopted, as follows: 



VII. METHODS FOR THE DETERMINATION OF INORGANIC PLANT CON- 

 STITUENTS. 



1. PREPARATION OF SAMPLE. 



The material must be thoroughly cleaned from all foreign matter, especially from adhering 

 soil. It is to be ground and preserved in carefully stopped bottles. 



2. DETERMINATION OF CARBON-FREE ASH. 



(a) Preparation of calcium acetate. 



Dissolve 20 grams c. p. calcium carbonate in c. p. acetic acid, and dilute to a liter. Evap- 

 orate 20 cc in a platinum dish, ignite gently, then strongly, to constant weight. The dish 

 must be weighed quickly. This gives the calcium oxid in 20 cc. 



An alternative method is to dissolve marble in hydrochloric acid, evaporate, and dry to 

 render silica insoluble, dissolve with water and a little acid, and precipitate iron and alumi- 

 num in the usual way. The calcium is then precipitated with ammonia and ammonium 

 oxalate in hot solution, the precipitate washed well, dried, ignited, and weighed. It is then 

 dissolved, and diluted so that 100 cc contains 1.1 grams calcium oxid. 



It is best to test the purity of this reagent by making blank determinations with it. 



(b) Preparation of ash. 



Moisten 10 to 20 grams substance with 40 cc calcium acetate, dry on a water bath, and 

 ignite, gently at first, then more vigorously. The quantity of calcium acetate used should 

 be sufficient to prevent fusion of the ash. Some form of apparatus must be used to prevent 

 volatilization, either Shuttleworth's a or Tucker's & or an ordinary platinum dish may be 

 used, fitted with a cover, like that described by Wislicenus.c The weight of the ash must 

 be corrected for lime, carbon dioxid, and carbon. 



aExp. Sta. Rec., 11: 304. 



b Ibid., 506. 



cZts. anal. Chem., 1901, 40: 441. 



(c) Determination of carbon dioxid. 



Using the ash prepared in (b), liberate the carbon dioxid with hydrochloric acid in any of 

 the usual forms of apparatus, determining the carbon dioxid evolved either by increase of 

 weight of potash bulbs or loss of weight of the apparatus. The former method is preferred. 



(d) Determination of carbon, sand, and silica. 



The residue from the carbon dioxid determination is transferred to a beaker or evaporating 

 dish, evaporated to dryness, and thoroughly dried and pulverized to render silica insoluble. 

 The dry residue, etc. [Same as p. 78, paragraph 2, to the end.] 



Subtract carbon, carbon dioxid, and calcium oxid added in the form of calcium acetate 

 from the ash, and calculate results as carbon -free ash. 



