1. Place 5 gms. of pulverized materials to be tested in a 
platinum or acid-leached glazed porcelain evaporating dish. 
2. To this sample, add 5 ml. of HCL (1:1) to form a slurry. 
Stir or mix to expose as much surface area of the sample as 
possible to the HCL. 
3. Evaporate over a water bath or other suitable heating 
apparatus. 
4. During this evaporation, add 5 ml. of HCL (1:1) at three 
appropriately spaced intervals. 
5. Add 5 ml. HCLO, (7:3), and proceed to total evaporation. 
6. After evaporation to dryness, place the dish in an oven 
(110°C) or other suitable apparatus to bake for forty minutes. 
7. Remove evaporating dish and allow to cool until moder- 
ately warm. 
8. Add to residue in dish, 5 ml. HCL (1:1), and 50 ml. 
distilled water to form a slurry. Stir with porcelain spatula or 
other suitable apparatus (no glass). 
9. Pass this heated mixture through an ashless, quantitative 
grade filter paper by means of vacuum filtration. 
10. Wash evaporating dish with small amounts of HCL 
(1:50), and pass this through the same filter. 
11. Pass 50 ml. of hot distilled water in 10 ml. increments also 
through the residue on the filter. 
12. Set aside this filter with residue. 
13. Place the filtrate (see 9) and washings (see 10, 11) in the 
original evaporating dish, in portions if necessary, and evapo- 
rate to dryness as in 6. 
14. Repeat steps 7 through 12. 
15. Place the two filters with residue (see 12), in a tared 
covered platinum crucible and place the crucible in a drying 
oven (110°C) for forty minutes. 
16. After drying, remove the covered crucible from the drying 
oven; place in a muffle furnace, and ignite to 1000°C for 
fifteen minutes. 
17. Remove the crucible from the muffle furnace and cool in 
a dessicator; weigh and repeat step 16, until cooled crucible 
demonstrates a constant weight. 
18. Record this constant weight. 
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