48. ANALYSIS OF FERROCYANIDE OF POTASSIUM.

a. Combustion with chromate of lead (§ 146. a.)

b. Estimation of the nitrogen by the method of VARRENTRAPP and WILL (§ 149.)

c. Estimation of the potass (as chloride of potassium) vide § 71.

d. Estimation of the iron, vide § 110. III. b.

e. Estimation of the water (§ 14. d.)

49. ANALYSIS OF QUININE.

a. Estimation of the carbon and hydrogen, vide § 146.

b. Estimation of the nitrogen (§ 149.)

c. Determination of the atomic weight.

a. From the double platinum salt (§ 94. a)

B. From the increase of weight upon the transmission of hydrochloric acid gas (§ 153. b.)

1. WATER DISTILLED FROM GLASS VESSELS. (§ 34. 1.) 42.41 grammes of water which had been distilled with extreme caution from a tall glass flask with a LIEBIG's condensing tube, left upon evaporation in a platinum basin, a residue weighing after ignition 0.0018 grm., consequently 73361

2. SULPHATE OF POTASS AND ALCOHOL, (§ 42. a.)

a. Ignited pure sulphate of potass was digested cold with absolute alcohol, for the space of several days, the solvent action of the alcohol being aided by frequent agitation of the mixture; the fluid was then filtered off, the filtrate diluted with water, and subsequently mixed with chloride of barium. It remained perfectly clear upon the addition of this reagent, but after the lapse of a considerable time it began to exhibit a slight opalescence. Upon evaporation to dryness there remained a very trifling residue, which manifested however a distinct reaction of sulphuric acid.

b. The same salt treated in the same manner, with addition of some pure concentrated sulphuric acid, yielded a filtrate, which upon evaporation in a platinum dish left a perfectly distinct fixed residue of sulphate of potass.

3. DEPORTMENT OF CHLORIDE

AND AT A HIGH TEMPERATURE.

OF POTASSIUM IN THE AIR, (§ 42. c.)

0.9727 grm. of ignited (not fused) pure chloride of potassium

were heated to dull redness in an open platinum basin, and kept ten minutes at this temperature, when loss of weight of 0.0007 gramme was observed; maintained for ten minutes longer in this state, the weight remained the same. Heated to bright redness and semi-fusion, the salt suffered a further loss of weight to the extent of 0.0009 gramme. Ignited intensely and to perfect fusion, it lost 0.0034 gramme, in addition to the former 0.0007 and 0.0009 gramme.

Eighteen hours exposure to the air produced not the slightest increase of weight.

4. SOLUBILITY OF POTASSIO-CHLORIDE OF PLATINUM IN ALCOHOL. (§ 42. d.)

a. In absence of free hydrochloric acid.

a. An excess of perfectly pure, recently precipitated, potassiochloride of platinum was digested for six days at from 59° to 68° F., with alcohol of 97.5 per cent., in a stoppered bottle, the solvent action of the alcohol being aided by frequent agitation of the mixture. 72 5 grammes of the perfectly colorless filtrate left upon evaporation in a platinum basin, a residue which dried at 212° weighed 0.006 grammes. The solution of one part of potassiochloride of platinum require therefore 12083 parts of alcohol of 97.5 per cent.

B. The same experiment was made with spirit of wine of 76 per cent. The filtrate was nearly colorless; upon evaporation, slight nigrescence ensued, in which account the residue was determined as platinum. 75.5 grammes yielded 0.008 gramme of platinum corresponding to 0.02 gramme of the potassio-chloride. One part of this salt dissolves accordingly in 3775 parts of spirit of wine of 76 per cent.

8. The same experiment was made with spirit of wine of 55 per cent the filtrate was distinctly yellowish. 63.2 grammes left 0.0241 gramme of platinum corresponding to 0.06 gramme of the potassio-chloride. One part of this salt dissolves accordingly in 1053 parts of spirit of wine of 55 per cent.

b. In presence of free hydrochloric acid.

Recently precipitated potassio-chloride of platinum was digested cold with spirit of wine of 76 per cent. containing an admixture of hydrochloric acid. The solution was yellowish; 67 grammes left, 0.0146 gramme of platinum, which corresponds to 0.0365 gramme of the potassio-chloride. One part of this salt, therefore, dissolved in 1835 parts of spirit of 76 per cent., containing an admixture of hydrochloric acid.

5. SULPHATE OF SODA AND ALCOHOL. (§ 43. a.)

Experiments made with pure anhydrous sulphate of soda, in the manner described at 2., showed that this salt comports itself both with pure alcohol, and alcohol containing sulphuric acid in admixture, exactly like the sulphate of potass.

6. DEPORTMENT OF THE IGNITED SULPHATE OF SODA IN THE AIR. (§ 43. a.)

2.5169 grammes of anhydrous sulphate of soda were exposed in a watch glass to the open air on a hot summer day. The first few minutes passed without any increase of weight, but after the lapse of five hours an increase of 0,0061 gramme was observed.

7. EXPERIMENTS WITH NITRATE OF SODA. (§ 43. b.)

a. 4.5479 grammes of pure nitrate of soda exposed in a state of fusion, to the air, (in April, the weather being fine,) exhibited after the lapse of twenty-four hours, an increase of weight of 0.0006 gramme.

b. 4.5479 grammes of pure nitrate of soda were dissolved in water, in a platinum basin, and pure nitric acid was added to the solution; the mixture then evaporated to dryness in the waterbath, and the residual mass cautiously heated to incipient fusion. The contents of the basin weighed, after cooling 4.5503 grammes. The mass was now again heated to complete fusion; after cooling it was found to weigh 4.5474 grammes.

8. DEPORTMENT OF CHLORIDE OF SODIUM IN THE AIR

(§ 43. c.)

4.3281 grammes of chemically pure intensely ignited (but not fused) chloride of sodium which has been cooled under a glass jar over sulphuric acid, acquired during forty-five minutes exposure to the (somewhat moist) air, an increase of weight of 0.0009 gramme.

9. DEPORTMENT OF CHLORIDE OF SODIUM UPON IGNITION WITH AND WITHOUT SAL AMMONIAC.

4.3281 grammes of chemically pure ignited chloride of sodium were dissolved in water in a moderately sized platinum basin, and pure sal ammoniac added to the solution, which was then evaporated and the residue gently heated until the evolution of salammoniac fumes had apparently ceased. The weight of the residue was now 4.3334 grammes. The residue was then again very gently ignited for about two minutes, and subsequently reweighed, when the weight was found to be 4.3314 grammes. After a few minutes strong ignition, the weight of the residue was 4.3275 grammes. After two minutes intense ignition, (upon which occasion white fumes were seen to escape,) the weight of the residue was found to be 4.3249 grammes.

10. DEPORTMENT OF SAL AMMONIAC UPGN EVAPORATION AND EXSICCATION. (§ 44. a.)

0.5625 gramme of pure and perfectly dry sal ammoniac were dissolved in water in a platinum basin, and the solution was subsequently evaporated and dried in the water-bath; the weight was now found to be 0.5622 gramme, (ratio 100: 99.94.) The mass was again heated for fifteen minutes in the water-bath, and afterwards re-weighed, when the weight was found to be 0.5612 grm. (ratio 100 99.77.) Exposed once more for fifteen minutes to the same temperature; the weight was afterwards found to be 0.5608 grammes, (ratio 100: 99.69.)