§ 124. ASH RICH IX CARBOITATES, POOR IN SILICA. 243 



The whole quantity of the asli, in whatever way ob- 

 tained, should be most carefully pulverized and mixed 

 together before any sample is taken for analysis. 



A. ASH RICH IN CARBONATES, AND POOR IN SILICA. 



124. a. Carbonic acid. — Determine this in 1-2 grms., 

 using nitric acid to expel the carbonic acid. 



h, Clllorine. — Estimate this in the nitric-acid solution 

 obtained in a^ after filtering out the insoluble portion. 



c. Silica, sand, and coal. — Moisten a portion (3-4 grms.) 

 in a flask, with concentrated nitric acid, add concentrated 

 hydrochloric acid, and digest the mixture for a long time 

 at an almost boiling heat. Rinse the whole into an evapo- 

 rating ciish, evaporate to dryness, moisten the residue with 

 hydrochloric acid, and proceed to eliminate and deter- 

 mine silica, sand, and coal, as directed in § 58, «, 3. 



If the ash contains no sandy particles, as may be shown 

 by the absence of any grittiness when the residue, insolu- 

 ble in hydrochloric acid, is stirred with the glass rod, the 

 boiling with sodic carbonate may be omitted, and nothing 

 need be done but collect the silica on a weighed filter, dry 

 it at 110°, weigh it, and ignite, and weigh it again, to 

 determine the un consumed carbon that may be mixed 

 with it. 



If there are more than a few centigrammes of this carbon 

 in three or four grammes of the ash, the substance has not 

 been properly incinerated, and very unreliable results 

 may be obtained in the analysis, particularly as regards 

 the phosphates and the alkalies. 



d. Complete analysis. — Bring the filtrate from the in- 

 soluble portion to a volume of 500 c.c, and examine it 

 according to Scheme IV., § 94. If more than traces of 

 manganic oxide are present, and it is desired to estimate 

 this base, proceed according to Scheme III., § 94. 



