, until
ash is white or grayish white, and weigh.

8. _Ash Insoluble in Acid--Official_

Boil the water-insoluble residue, obtained as directed under 9, or the
total ash obtained as directed under 7, with 25 cc. of 10-percent
hydrochloric acid (sp. gr. 1.050) for 5 minutes, collect the insoluble
matter on a Gooch crucible or an ashless filter, wash with hot water,
ignite and weigh.

9. _Soluble and Insoluble Ash--Official_

Heat 5 to 10 grams of the sample in a platinum dish of from 50 to 100
cc. capacity at 100 deg. C. until the water is expelled, and 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. Add water to the ash, in the platinum dish, heat
nearly to boiling, filter through ash-free filter paper, and wash with hot
water until the combined filtrate and washings measure to about 60 cc.
Return the filter and contents to the platinum dish, carefully ignite,
cool and weigh. Compute percentages of water-insoluble ash and
water-soluble ash.

10. _Alkalinity of the Soluble Ash--Official_

Cool the filtrate from 9 and titrate with N/10 hydrochloric acid, using
methyl orange as an indicator.

Express the alkalinity in terms of the number of cc. of N/10 acid per 1
gram of the sample.

11. _Soluble Phosphoric Acid in the Ash--Official_

Acidify the solution of soluble ash, obtained in 9, with dilute nitric
acid and determine phosphoric acid (P_2_O_5). For percentages up to 5
use an aliquot corresponding to 0.4 gram of substance, for percentages
between 5 and 20 use an aliquot corresponding to 0.2 gram of substance,
and for percentages above 20 use an aliquot corresponding to 0.1 gram of
substance. Dilute to 75-100 cc., heat in a water-bath to 60 deg.-65 deg.
C., and for percentages below 5 add 20-25 cc. of freshly filtered molybdate
solution. For percentages between 5 and 20 add 30-35 cc. of molybdate
solution. For percentages greater than 20 add sufficient molybdate
solution to insure complete precipitation. Stir, let stand in the bath
for about 15 minutes, filter _at once_, wash once or twice with water by
decantation, using 25-30 cc. each time, agitate the precipitate
thoroughly and allow to settle; transfer to the filter and wash with
cold water until the filtrate from two fillings of the filter yields a
pink color upon the addition of phenolphthalein and one drop of the
standard alkali