Repository: UIHistories Project: Board of Trustees Minutes - 1878 [PAGE 180]

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180 collected on a filter, washed with ammoniacal water, dried, strongly ignited and weighed. Sulphuric Acid.—The 40 grams weighed off for the estimation of the alkalies was digested in 120 c.c. of hydrochloric acid (sp.gr. 1.15) for 48 hours, diluted and filtered. T h e solution was concentrated, iron oxidized, and finally brought to dryness. T h e silica was removed. T h e solution was boiled, and then barium chloride in sufficient quantity to precipitate sulphuric acid present added. The precipitate thus formed was collected, after standing for some time on a filter, ignited and weighed. Alkalies.—The above filtrate was treated with ammonium carbonate in excess, t h e mixture boiled and the precipitate filtered off and washed. T h e filtrate and washings were brought to dryness in a platinum dish, then ignited to expel ammonium salts. T h e residue was then treated with a concentrated solution of oxalic acid, dried, ignited to dull redness, water added and filtered. The solution was then acidulated with hydrochloric acid and brought to dryness in a platinum dish of known weight, gently ignited, cooled and weighed. This weight represented the amount of potassa and soda, as chlorides, in t h e soluble portion of 40 grams of soil. T h e weighed chlorides were dissolved in dilute hydrochloric acid, an excess of platinic chloride added and brought to dryness on a water bath ; the residue agitated with a mixture of alcohol and water, and finally filtered on a weighed filter, washed with alcohol and water, dried at 100 c. and the residue weighed as 2 k cl. pt cl. 4 and estimated as K. 20. T o find the Na. 2 O subtract the weight of k cl. which t h e potassa will form from the sum of t h e alkaline chlorides, and the difference will equal the N a Cl. which is estimated as N a 2 O.

B. PORTION INSOLUBLE I N HYDROCHLORIC ACID.

The portion insoluble in hydrochloric acid was dried at 100 dg. c for several days. I t was then taken from the filter as far as practicable, the filter ignited and the ash added to the rest. T h e whole was then weighed and the amount of insoluble matter ascertained. Of the dried insoluble matter there was taken for:

G E N E R A L ESTIMATION A L K A L I E S AND ORGANIC M A T T E R 2 2 grams. grams.

The portion for t h e estimation of the alkalies and organic was thoroughly ground in an agate mortar.

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Silicicic Acid.—The two grams reserved for the general estimation were fused with four parts of an equal mixture of carbonates of potassium and sodium. W h i l e still hot, the crucible was set in water in a porcelain dish and thus allowed to cool. The fused mass was then digested with water in a porcelain dish on a water bath, and then an excess of hydrochloric acid was added and the whole brought completely to dryness; the residue moistened with hydrochloric acid, and finally water added and filtered. The residue thoroughly ignited and weighed as Si O 2.