216 § 112. FERTILIZERS. 



8. Ferric oxide, etc. — Ignite the remainder of the 

 residue obtained in 3, dissolve the ash in hydrochloric 

 acid, eliminate silica by evaporation to dryness, and exam- 

 ine the filtrate from the silicic acid according to Scheme 

 L, § 94. 



A. The total residue, insoluble in water, obtained in </, 

 is dried in the steam-chamber, exposed to the air 24 

 hours, and weighed in this air-dried condition ; then cut 

 up the fibrous parts of it with the shears, and grind the 

 whole to a fine powder in the porcelain mortar or steel milll 



L Water. — In 10 grms. of this powder determine hy- 

 groscopic water by heating to 110° C. 



2. Organic matter. — Ignite the dry residue obtained 

 in a, and determine the loss (§ 91), and determine car- 

 bonic acid and chlorine, if desired, in the ash. 



3. Nitrogen. — To determine the nitrogen in undecom- 

 posed organic matter in the manure, a part of which might 

 be insoluble in water, and hence found here, ignite 1-2 

 grms. of the powder with a considerable proportion of 

 soda-lime (§ 85). 



4. Ferric oxide, etc. — Ignite 30-40 grms. of the 

 powdered insoluble residue in a platinum dish, and in 

 3-6 grms. of the properly prepared ash (§ 123, c), accord- 

 ing to the proportion of sand present, eliminate silica and 

 sand, and analyze the remainder according to Scheme I. 

 or II, 



