128 

 12 



METHODS OF ANALYSIS 



Table 13. 

 Corrections for temperature. 



[Chap. 



13 



Method I.— Official. 



Heat 5-10 grams of the sample in a 50-100 cc. platinum dish at 100°C. until the 

 water is expelled, add a few drops of pure olive oil, and heat slowly over a flame 

 until swelling ceases. Then place the dish in a muffle and heat at low redness until 

 a white ash is obtained. 



14 



Method II.— Official. 



Carbonize the mass at a low heat, dissolve the soluble salts in hot water, burn 

 the residual mass as directed in 13, add the solution of soluble salts, and evaporate 

 to dryness at 100°C., ignite gently, cool in a desiccator, and weigh. 



1 5 Method III.— Official. 



Saturate the sample with sulphuric acid, dry, ignite gently, then burn in a muf- 

 fle at low redness. Deduct one tenth of the weight of the ash, and calculate the 

 per cent. 



1 6 QUANTITATIVE ANALYSIS OF THE ASH.— OFFICIAL. 



Proceed as directed under III. 



1 7 SOLUBLE AND INSOLUBLE ASH.— TENTATIVE. 



Ash the material as directed under 13 or 14. Add water to the ash in the plati- 

 num dish, heat nearly to boiling, filter through an ashless filter paper, and wash 

 with hot water until the combined filtrate and washings measure about 60 cc. Re 



