. If sulphuretted hydrogen be present, along with carbonic acid, the separation of these two is a problem of some diffi culty, Air. Kirwan recommends, that a graduated glass vessel, completely filled with the mixture, he removed into a ves _ sel containing nitrous acid. This instantly condenses the sulphuretted hydrogen, but not the carbonic acid gas. It seems to be a more eligible mode to condense the sulphtreetted hydrogen by oxymuri atic acid gas Obtained from hyper-oxymuriate of potash,) adding the latter gas very cautiously,as long as it pro duces.any condensation. Or, perhaps, a better plat of effecting the separation is the following, recommended by Mr. Hen ry : half fill a graduated phial with the , mixed carbonic acid and sulphuretted by• drogen gases, and expel the rest of the . water by oxymuriatic acid gas. Let the • mouth of the bottle be then closed with a well ground stopper, and let the mix ture be kept hours. Then withdraw the stopper tinder water, a quantity of which fluid will immediately rush in. Allow the bottle to stand half an hour without agitation. The redun . clant oxymuriatic acid gas will thus be absorbed ; and very little of the carbonic acid will disappear. Supposing that, to ten cubic inches of the mixed gases, ten inches of oxymuriatic gas have been added, and that, after absorption, by standing over water, five inches re main, the result of this experiment shows that the mixture consisted of equal parts of sulphuretted hydrogen and carbonic acid gases.
Whenever this complicated admixture of gases occurs, as in the Harrowgate, and in some of the Cheltenham waters, it is advisable to operate separately on two portions of gas, with the view to deter mine, by the one, the quantity of carbo nic acid and sulphuretted and that of azote and oxygen by the other. In the latter instance, remove both the absorbable gases by caustic potash, and examine the remainder in the manner al ready directed.
Nitrogen gas sometimes occurs in mi neral waters, almost in an unmixed state. When this happens, the gas will be known by the characters already describ ed as belonging to it. Sulphureous acid gas may be detected by its peculiar %mell of burning sulphur, and by its discharg ing the colour of an infusion of roses, which has been reddened by the smallest quantity of any acid adequate tp the ef fect.
(a) The water should next be evaporat ed to dryness. The dry mass, when col lected and weighed, is to be put in a bottle, and highly rectified alco hol poured on it, to the depth of an inch. After having stood a few hours, and been occasionally shaken, pour the whole on a filter, wash it with a little more alcohol, and dry and weigh the remainder.
(b) To the undissolved residue add nine times its weight of cold distilled water; shake the mixture frequently ; and, after some time, filter ; ascertaining the loss of weight.
(c) Boil the residuum, for a quarter of an hour, in something more than five hundred' times its weight of water, and afterwards filter.
(d) The residue, which must be dried and weighed, is no longer soluble in wa ter or alcohol. If it lies a brown colour, denoting the presence of iron, let it be moistened with water, and exposed to the sun's rays for seine weeks.
I. The solution in alcohol (a) may con tain one or all of the following salts mu riates of lime, magnesia, or barytes, or nitrates of the same earths. Sometimes,
also, the alcohol may take up sulphate of iron, in which the metal is highly oxy dized, as will appear by its reddish-brown 1. In order to discover the quality and quantity of the ingredients, evaporate to drvness ; weigh the residuum ; add above half its weight of strong sulphuric acid ; and apply a moderate heat. The muri riatic or nitric acid will be expelled, and will bit known by the colour of their fumes ; the former being white, and the latter orange-coloured.
2. To ascertain whether lime or mag nesia he the basis of the salts, let the heat be continued till no 'more fumes arise, and let it then be raised to expel the ex cess of sulphuric acid. To the dry mass, add twice its weight of distilled water. This will take up the sulphate of magne sia, and leave the sulphate of lime. The two sulphates may be separately decom posed, by boiling with three or tour times their weight of carbonate of pot ash. The carbonates of lime and magne sia, thus obtained, may be separately dis solved in muriatic acid, and evaporated. The weight of the dry salts will inform us how much of each the alcohol had taken up. Lime and magnesia may also be se parated by the use of phosphate of soda.
II. The watery solution (b) may con tain a variety of salts, the accurate sepa ration of which from each other is a prob lem of considerable difficulty.
1. The analysis of this solution may be attempted by crystallization. For this purpose let one half be evaporated by a very gentle heat, not exceeding 80° or 90°. Should any crystals appear on the surface of the solution, while hot, in the form of a pellicle, let them he separated and dried on bibulous paper. There are mu•iate of soda, or common salt. The re maining solution, on cooling very gradu ally, will perhaps afford crystals distin guishable by their form and other quali ties. When various salts, however, are contained in the same solution, it is ex tremely difficult to obtain them suffi ciently distinct to ascertain their kind.
2. The nature of the saline contents must therefore be examined by tests, or re-agents.
The presence of an uncombined as well as uncombined acids, will be dis covered:by the stained papers, and tests already pointed out. The vegetable al kali, or potash, may be distinguished from the mineral, or soda, by muriate of platina.
If neutral salts he present in the so lution, we have to ascertain both the na ture of the acid, and that of the base. This may be done by attention to the rules already given for the application of tests, which it is unnecessary to repeat in this place.
III The solution by boiling water con tains scarcely any thing besides sulphate of lime.
IV. The residuum (d) is to be digested in distilled vinegar, which takes up mag nesia and lime, but leaves, undissolved alumine and higlily oxydized iron. Eva porate the solution to dryness. If it con tain acetate of lime only, a substance will be obtained which does not attract mois ture from the air ; if magnesia be pre sent, the mass will deliquesce. To sepa rate the lime from the magnesia, proceed The residue, insoluble in acetous acid, may contain alumine, iron, and silex. The two first may he dissolved by muria- j tic acid, from which the iron may be pre- I cipitated, first by prussiate of potash, I and the alumine afterward by a fixed al kali.