Acetate of Lead.

blue colour restored green and opaque white precipitate, redissolved by acetic acid

To ascertain the relative proportions of the saline ingredients, one pint, imperial measure, was boiled with subcarbonate of Soda; after subsidence it no longer yielded a precipitate with oxalate of ammonia, or carbonate of ammonia and phosphate of soda.

The precipitate was washed, and redissolved in muriatic acid. Sulphuric acid was then added, and the mixture boiled to dryness, and heated to drive off the excess of acid; the mixed sulphates were digested in a small quantity of water, the solution. evaporated to dryness left 6.6 grains of sulphate of magnesia, equivalent to 5.3 grains of chloride of magnesium.

The undissolved portion of sulphate of lime weighed 13.2 grains, equivalent to 10.9 grains of of chloride of calcium.

The saline residuum, after the separation of the lime and magnesia, displayed the negative characters which belong to chloride of sodium.

The crystals separated on boiling, dissolved readily in nitric acid; they furnished a precipitate with oxalate of ammonia, and had the rhomboidal form of carbonate of lime. Their weight was 1.7 grains from a pint. Considered as carbonate of lime, separated from chloride of calcium by sodium, existing in water as bicarbonate of soda; 1.7 grains will represent 2.6 grains of bicarbonate of soda.

To a pint of water boiled to expel the gases, which would confuse the result, nitrate of silver was added until it ceased to produce any effect; the precipitate weighed 313 grains. This indicates 76 grains of chlorine, of which the calcium, equivalent to the sulphate of lime obtained, would combine with 7 grains. The magnesium would saturate 3.96 grains, leaving 65 for soda, indicating of chloride of sodium 108.4 grains.

To separate the gaseous contents of the water, four pints were boiled in a glass retort with slips of platina, until the quantity of gas received ceased to increase.

It was received in a narrow vessel, over a small portion of water, in preference to mercury, on account of the action of sulphuretted hydrogen on that metal.

It measured 17 cubic inches at the temperature of 60o, equal to 34 inches per gallon. A tube, graduated into hundredths of a cubic inch, was filled with and transferred to a bottle containing carbonate of lead, diffused in a small quantity of water; on agitation an absorption took place, amounting to .46 of a cubic inch, or 15.64 inches, from the gases contained in a gallon.

The residual gas was treated in the same manner with liquid potash; the absorption was 8 per

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cent of the originally operated on, or 2.72 cubic inches from the gases in a gallon.

The method of gaseous analysis by absorption, is decidedly superior to the formation of precipitates; some sources of error are common to both; but the quantity of precipitate from the gas yielded by a moderate quantity of water, is so minute, that very small errors, during the several processes of formation, collection, washing, drying, and weighing, have a material influence on the quantity of gas denoted by the final result. A loss or increase of one-hundredth of a grain on the carbonate of lime, produced in operating on a pint and a half of water, would give rise to an error of one cubic inch in the calculation for a gallon. The eudeometrical method, which was pursued, is short, easy, and susceptible of great precision; an error in the carbonic acid of two whole divisions of the tube, would scarcely effect by half a cubic inch the quantity in a gallon.

The proportion of gas, 46 per cent, which was not absorbed by carbonate of lead or by potash, was mixed with twice its bulk of oxygen, and exploded by the electric spark. On agitation with potash after the explosion 60 measures were absorbed; one third of this dimunition was carburetted hydrogen gas; viz. 20 per cent, or 6.8 cubic