A paper on this subject, which appeared in the Repertory of Arts, vol. ii. p. 425, induced the Rev. W. Tooke to publish some remarks in vol. iii. p. 95, of that work, from which the following is an extract, respecting the spontaneous inflammation of animal and vegetable substances. "One Rude, (says he,) an apothecary at Bautzen, had prepared a pyrophorus from rye-bran and alum. Not long after he had made the discovery, there broke out, in the next village of Nauslitz, a great fire, which did much mischief, and was said to have been occasioned by the treating of a sick cow in the cow-house. Mr. Rude knew that the countrymen were accustomed to lay an application of parched rye-bran to their cattle, for curing the thick neck; he knew also that alum and rye-bran, by a proper process, yielded a pyrophorus; and now, to try whether parched rye-bran alone would have the same effect, he roasted a quantity of it by the fire, till it had acquired the colour of roasted coffee. ' This roasted bran he wrapped up in a linen cloth; in a few minutes there arose a strong smoke, with a smell of burning. Soon after, the rag grew as black as tinder, and the bran, now become hot, fell through it on the ground in little balls. Mr. Rude repeated the experiment, and always with the same result. Who now will doubt, that the frequency of fires in cowhouses, which in those parts are mostly wooden buildings, is occasioned by this practice, of binding roasted bran about the necks of the cattle?"

Montet relates, in the Memoires de l'Academie de Paris, 1748, that animal substances kindle into flame; and that he himself has been witness to the spontaneous accension of dunghills. The woollen stuff prepared at Sevennes, named Emperor's stuff, has kindled of itself, and burnt to a coal. It is usual for this to happen to woollen stuffs, when in hot summers they are laid in a heap, in a room but little aired. In June, 1781, this happened at a woolcomber's in Germany, where a heap of wool-combings, piled up in a close warehouse seldom aired, took fire of itself. This wool burnt from within outwards, and became quite a coal; though neither fire nor light had been used at the packing. In like manner cloth-workers have certified, that after they have bought wool that was become wet, and packed it close in their warehouse, this wool has burnt of itself. The spontaneous accension of various matters from the vegetable kingdom, as wet hay, corn, and madder, and at times wet meal and malt, is well known. Hemp, flax, and hemp-oil, have also often given rise to dreadful conflagrations.

In the spring of 1780, a fire was discovered on board a frigate lying in the roads off Cronstadt, which endangered the whole fleet. After the severest scrutiny, no cause of the fire was to be found; and the matter remained without explanation, but with strong surmises of some wicked incendiary. - In August, 1780, a fire broke out at the hemp magazine at St. Petersburg, by which several hundred thousand poods (about 361b. English) of hemp and flax were consumed. The walls of the magazine are of brick, the floors of stone, and the rafters and covering of iron; it stands alone on an island in the Neva, on which, as well as on board the ships lying in the Neva, no fire is permitted. - In St. Petersburg, in the same year, a fire was discovered in the vaulted shop of a furrier. In these shops, which are all vaults, neither fire nor candle is allowed, and the doors of them are all of iron. At length the probable cause was found to be, that the furrier, the evening before the fire, had got a roll of new cerecloth, and had left it in his vault, where it was found almost consumed. - In the night between the 20th and 21st of April, 1781, a fire was seen on board the frigate Maria, at anchor, with several other ships, in the roads off the island of Cronstadt; the fire was, however, soon extinguished, but, by the severest examination, nothing could be extorted concerning the manner in which it had arisen. The garrison was threatened with a scrutiny that should cost them dear; and while they were in this cruel suspense, the wisdom of the sovereign gave a turn to the affair, which quieted the minds of all, by pointing out the proper method to be pursued by the commissioners of inquiry, in the following order to Czernichef: "When we perceived, by the report you have delivered in of the examination into the accident that happened on board the frigate Maria, that, in the cabin where the fire broke out, there were found parcels of matting, tied together with packthread, in which the soot of burnt fir-wood had been mixed with oil, for the purpose of painting the ship's bottom, it came into our mind, that, for the fire which happened last year at the hemp-warehouses, the following cause was assigned; that the fire might have proceeded from the hemp being bound up in greasy mats, or even from such mats having lain near the hemp: therefore, neglect not to guide your farther inquiries by this remark."

As, upon juridical examination as well as private inquiry, it was found that, in the ship's cabin, where the smoke appeared, there lay a bundle of matting, containing Russian lamp-black, prepared from fir-soot moistened with hemp-oil varnish, which was perceived to have sparks of fire in it at the time of the extinction, the Russian admiralty gave orders to make various experiments, to see whether a mixture of hemp-oii varnish and the forementioned Russian black, folded up in a mat and bound together, would kindle of itself. They shook 401b. of fir-wood soot into a tub, and poured about 351b. of hemp-oil varnish upon it; this they let stand for an hour, after which they poured off the oil. The remaining mixture they now wrapped up in a mat, and the bundle was laid close to the cabin where the midshipmen had their birth. Two officers sealed both the mat and door with their own seals, and stationed a watch of four officers, to take notice of all that passed during the whole night; and as soon as any smoke should appear, immediately to give information to the commandant of the port. The experiment was made on the 26th of April, about eleven o'clock a. m. in presence of all the officers. Early on the 27th, about six o'clock a. m. a smoke appeared, of which the chief commandant was immediately informed: he came with speed, and, through a small hole in the door, saw the mat smoking. He dispatched a messenger to the members of the commission; but as the smoke became stronger, and fire began to appear, he found it necessary to break the seals and open the door. No sooner was the air thus admitted, than the mat began to burn with greater force, and presently it burst into a flame.

The Russian admiralty, being now fully convinced of the self-enkindling property of this composition, transmitted their experiment to the Imperial Academy of Sciences; who appointed Mr. Georgi, a very learned adjunct of the academy, to make farther experiments on the subject. Three pounds of Russian fir-black were slowly impregnated with 51b. of hemp-oil varnish; and when the mixture had stood open five hours, it was bound up in linen. By this process it became clotted; but some of the black remained dry. When the bundle had lain sixteen hours in a chest, it was observed to emit a very nauseous, and rather putrid smell, not unlike that of boiling oil. Some parts of it became warm, and steamed much; eighteen hours after the mixture was wrapt up, one place became brown, emitted smoke, and directly afterwards glowing fire appeared. The same thing happened in a second or third place; though other places were scarcely warm. The fire crept slowly around, and gave a thick, grey, stinking smoke. Mr. Georgi took the bundle out of the chest, and laid it on a stone pavement; when, on being exposed to the free air, there arose a slow burning flame, a span high, with a strong body of smoke. Not long afterwards, there appeared, here and there, several chaps, or clefts, as from a little volcano, the vapour issuing from which burst into flames. On his breaking the lump, it burst into a very violent flame, full three feet high, which soon grew less, and then went out. The smoking and glowing fire lasted six hours; and the remainder continued to glow without for two hours longer. The grey earthy ashes, when cold, weighed five and a half ounces. Mr. Tooke concludes with a case of self-accen-sion, noticed by Mr. Hagemann, an apothecary, at Bremen. He prepared a boiled oil of hyoscymnus, or henbane, in the usual way, with common oil. The humidity of the herb was nearly evaporated, when he was called away by other affairs, and was obliged to leave the oil on the fire. The evaporation of the humidity was hereby carried so far, that the herb could easily be rubbed to powder. The oil had lost its green colour, and had become brownish. In this state it was laid on the straining cloth, and placed in the garden, behind the house, in the open air. In half an hour, on coming again to this place, he perceived a strong smoke there, though he thought the oil must have long been cooled: on closer inspection, he found that the smoke did not proceed from the oil, but from the herb on the straining cloth; at the same time the smell betrayed a concealed fire. He stirred the herb about, and blew into it with a bellows, whereupon it broke out into a bright flame.