Page:Experimental researches in chemistry and.djvu/199

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On Sulphiric Acid and Napthaline.

four parts by weight of cold sulphuric acid were put into a bottle, well shaken, and left for thirty-six hours. The mixture then contained a tenacious deep red fluid, and a crystalline solid; it had no odour of sulphurous acid. Water being added, all the liquid and part of the solid was dissolved; a few fragments of naphtha line were left, but the greater part was retained in solution. The diluted fluid being filtered was of a light brown tint, transparent, and of an acid and bitter taste.

For the purpose of combining as much naphtha line as possible with the sulphuric acid, 700 grains with 520 grains of oil of vitriol were warmed in a Florence flask until entirely fluid, and were well shaken for about 30 minutes. The mixture was red; and the flask being covered up and left to cool, was found after some hours to contain, at the bottom, a little brownish fluid, strongly acid, the rest of the contents having solidified into a highly crystalline mass. The cake was removed, and its lower surface having been cleaned, it was put into another Florence flask with 300 grains more of naphtha line, the whole melted and well shaken together, by which a uniform mixture was obtained, but opake and dingy in colour. It was now poured into glass tubes, in which it could be retained and examined without contact of air. In these the substance was observed to divide into two portions, which could easily be distinguished from each other, whilst both were retained in the fluid state. The heavier portion was in the largest quantity; it was of a deep red colour, opake in tubes half an inch in diameter, but in small tubes could be seen through by a candle, or sunlight, and appeared perfectly clear. The upper portion was also of a deep red colour, but clear, and far more transparent than the lower: the line of separation very defined. On cooling the tubes, the lighter substance first solidified, and after some time the heavier substance also became solid. In this state, whilst in the tube, they could with great difficulty be distinguished from each other.

These two substances were separated, and being put into tubes, were further purified by being left in a state of repose at temperatures above their fusing-points, so as to allow of separation; and when cold, the lower part of the lighter substance and the upper, as well as the lower part of the heavier substance, were set aside for further purification.