VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 465 



mixture, and distilled it, in 24 hours, with a gentle heat. On the fluid swam a 

 white compact substance, and some small particles of the same kind lay at the 

 bottom, which however rose, on the application of heat, and swam about with 

 the rest. 



Exper. 58 to 63. I poured the whole distillation back on the salt, and, by means 

 of a digesting heat, again drew off a fluid, which appeared covered with a thin fat 

 skin. I then poured the fluid back; distilled it again, and thus repeated the pro- 

 cess 3 times more. No phenomenon particularly remarkable appeared, except 

 that the thin fat skin became more inconsiderable, and at last seemed almost 

 to vanish. 



Exper. 64. The salt separated from the fluid, by the gentle distillation in exper. 

 63, emitted now, by the force of additional heat, dark red vapours, as is usual in 

 strong nitrous acid. When the distillation was at an end, the retort was exposed 

 to an open fire; but, during this operation, no black matter appeared; nor was 

 any coal separated from the mass, on dissolving it in distilled water.* — Exper. 65. 

 I now tried the effect of a mixture of 4 dr. of strong vitriolic acid, and ] 2 dr. of 

 the muriatic acid, repeating the usual digestion and distillation 6 times. I shall 

 pass over other circumstances, and only mention, that after the 6th distillation of 

 the fluid, a stronger heat, and at length an open fire, was applied; but hardly any 

 fluid was produced, though the fire was so violent, that the Whole mass appeared to be 

 melted down into one uniform compact substance. — Exper. 66. The vessels having 

 cooled, the mass was of a light milky colour throughout, without the least mix- 

 ture of brown or black, or any other indication of coal.-j- Being some time 

 exposed to the air, it became moist, and for a long time attracted much water, 

 which I caused to run off. At last it remained pretty dry; but the mass seemed to 

 have diminished, by at least 4- part. 



Here I shall stop, for the present, in the description of my experiments; which 

 sufficiently tend to prove, in a general way, the decomposition of sedative salt, and 

 to show, that one of its component parts is inflammable matter, which may be 

 converted into coal. I obtained of true coal, mixed with some earth, exper. 33 

 and 54, according to the above-described experiments, (exper. 22, 26 — 30), 

 30f g r « m tne whole; and by other experiments, often repeated, in general, l-±- gr. 

 more or less. Every other substance liable to be changed into coal, as gum, tartar, 

 sugar, &c. suffers this change by a gentle heat, and deflagrates with nitre, in the 

 degree of heat necessary to melt the former. But sedative salt can bear a red heat 

 for many hours, without showing any signs of becoming coal, of burning, or of 

 deflagration. Astonishing phenomenon! What menstruum preserves it so se- 

 curely against the assault of force, in a dissolved state, and yet suffers itself to be 



* Here the nitrous acid seemed to destroy, and carry off, the inflammable matter, sooner than it 

 could become coal ; as it had before occasioned the oily and fat substance to vanish, in the beginning of 

 this experiment. — Orig. 



f Perhaps here also the remark contained in the former note holds good : yet I am rather of opinion, 

 that the vitriolic acid did not operate with sufficient strength to separate the component parts.— Orig. 



VOL. XVIII. 3 O 



