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such as hemp, cotton, matting, &c. had been stored, a number of experiments were instituted to prove the fact Among the most important of these, those by Mr. Georgi and a committee of the Royal Academy at Petersburgh, in the year 1781, in consequence of the destruction of a frigate in the harbour of Cronstadt; the conflagration of a large hemp magazine in the same place, in the same year; and a slight fire on board another frigate, in the same port, in the following year, deserve our particular notice. “ Forty pounds of fir wood soot were soaked with about thirty-five pounds of hemp-oil varnish, and the whole wrapped up in a mat and put into a close cabin. In about sixteen hours it was observed to give out smoke, which rapidly increased, and when the door was opened and the air freely admitted, burst into a flame.”
Three pounds of fir-black were mixed with five pounds of hemp-oil varnish, and the whole bound up in linen, and shut up in a chest, in sixteen hours it emitted a very nauseous putrid smell and steam, and in two hours afterwards it was actually on fire, and burned to ashes.
The presence of lampblack, or any other carbonaceous mat. ter, is not, however, necessary; for a spontaneous inflammation will take place in hemp or cotton, simply soaked in any of these expressed oils, when in considerable quantity, or under circumstances favourable to this process, as in very hot weather, or closely shut up. “ An accident of this kind happened at Gains. borough in Lincolnshire, in July 1794, with a bale of yarn of one hundred and twenty pounds, accidentally soaked in rape oil, which, after remaining in a warehouse for several days, began to smoke and finally burst into a flame." A similar accident, with a very small quantity of materials, happened at Bombay. A bottle of linseed oil had been left standing on a chest, this had been thrown down by accident in the night, the oil had run into the chest, which contained some coarse cotton cloth, and in the morning the cloth was found scorching hot, and reduced nearly to tinder, and the wood of the chest charred on the inside.
Similar to this, is the spontaneous combustion of wool or wool. en yarn, which has occasionally happened when large quantities have been kept heaped up in rooms, little aired and in hot weather. The oil with which wool is dressed appears the chief agent in this combustion.
Rye flour roasted till half parched, and of the colour of cof. fee, and wrapped up in a linen cloth, has been found to heat violently, and to destroy the cloth. Wheat flour, heated in large quantities and highly dried, has been known to take fire in hot weather, causing accidents in granaries and bakers' shops. Count Morrozzo, in the Memoirs of the Turin Academy, notices an ac. cident of this kind, in a flour warehouse at Turin, where there were three hundred sacks of flour. It began by a violent explosion on a lamp being brought into the warehouse and the whole was soon in flames. We have likewise many curious instances on record of the spontaneous combustion of the human body, which occurred in England, France, Italy, and elsewhere; a minute account of which may be found in the Repertory, vol. 2, and Philosophical Transactions, vol. 43 and 64.
The many accidents which occur, likewise, at our gunpowder manufactories, ought to induce those, who are concerned therein, to examine the causes which frequently produce explosions, and to adopt such means a3 will in future prevent, not only the loss of property, but the lives of those who are immediately engaged in the various operations of powder making.
The workmen, usually employed, have only a general idea of the process of making powder, without the least acquaintance with those latent causes, which, in a moment, may put a period to their existence.
Mr. de Caussigni appears to have been the first, who obseryed that charcoal was capable of being set on fire by the pressure of millstones. Mr. Robin, commissary of the powdermills of Esonne, has given an account, in the Annales de Chimie, No. 35, p. 93, of the spontaneous inflammation of charcoal made from the blackberry bearing alder. This accident occurred May 23, 1801, in the box of the bolter, into which it had been sifted. This charcoal, made two days before, had been ground in the mill without any signs of ignition. The coarse powder that remained in the, bolter experienced no alteration. The light undulating flame, “ unextinguishable by water," that appeared on the surface of the sifted charcoal, was of the nature of inflammable gas. The moisture of the atmosphere, of which fresh made charcoal is very greedy, was supposed to have concurred in the development of the inflammable gas, and the combustion of the charcoal. VOL. III.
It has been observed that charcoal, powdered and laid in large heaps, heats strongly. Alder charcoal has been seen to take fire in the warehouse, in which it has been stored. Mr. Malet, commissary of gunpowder at Pontailler, near Dijon, has seen charcoal take fire under the pestle. He also informs us that when pieces of saltpetre and brimstone were put into the charcoal mortar, the explosion took place between the fifth and sixth stroke of the pestle. In consequence of the precaution now taken to pound the charcoal, brimstone and nitre separately, no explosions take place, and time is gained in the fabrication, since the paste is made in eight hours, that formerly required twenty-four.”
Seeing that charcoal is liable to spontaneous inflammation by laying in a heap; by the firessure of a millstone, or the operation of pounding, it ought to teach those, who work in powdermills, to be careful in all their operations. Saltpetre will detonate with, or in. flame charcoal, and other easily inflammable bodies at a red heat; hence operators should be extremely cautious when they unite charcoal with their salt petre in a heated caldron (which is the practice of some) lest the coal be ignited or the caldron become red hot, and a detonation be the consequence, which may prove an injury to themselves and the property of their employers: nothing but a strict attention to the degree of heat will prevent such a fatal catastrophe. When nitre is deprived of its water of crystallization in a caldron care should be taken not to increase “the heat beyond one hundred and twenty of Farenheit, taking care to stir it all the while by which it will be brought to the consistence of fine sand, and is now ready to be manufactured into gunpowder.
The spontaneous combustion of charcoal ought likewise to put those persons on their guard, who are in the habit of keeping large quantities of powdered charcoal in their distilleries and liquor stores, for the purification of spiritous liquors, where the effects would indeed be terrible, should a combustion take place during the night. While on the subject of charcoal, I cannot help expressing my surprise that a patent should have been obtained in the United States, within a few years past, for the discovery of the use of charcoal for the purification of malt or other spirits from their empyreumatic oils; as the experiments of Lawitz and Crell had been published in many periodical works. Lawitz, a chymist of Petersburgh, was the first who made the discovery public; and
Crell, in his Chymical Journal, published in 1778, and translated in 1791, communicated to the world many interesting experiments on the subject of the purifying property of charcoal. Among many experiments which he related, the following, perhaps, may be particularly worthy of attention: 1. Common vinegar, on being boiled in a matrass with charcoal powder, became perfectly limpid like water. 2. Honey was deprived of its peculiar smell. 3. Brown, putrid, and stinking water, was not only immediately deprived of its offensive smell, by means of charcoal powder, but was also rendered transparent. Hence it would probably be of use for preserving fresh water during sea voyages, to add about five pounds of coarse charcoal powder to every cask of water, especially as the charcoal might easily he separated by filtering, whenever wanted, through a linen bag. Lastly, spirits distilled from malt or other grain, show by the smell evidently that their strength is much increased by purification with charcoal, without the help of distillation, insomuch that persons who were not informed of the manner in which the purification was effected, have taken such spirits for rectified spirits of wine. I divided, says Crell, ten pounds of ardent spirits into ten equal portions and added charcoal powder in the following increased proportions:
“ Half a dram of charcoal powder produced scarcely any alteration in the smell, and the spirits had not become quite clear even after six months. One dram occasioned hardly any perceptible diminution of the smell, and the spirit did not become clear till after the space of four months. With two drams the spirit became clear in two months.
6i Four drams occasioned a very perceptible diminution of the smell, and the powder completely settled in the course of a month.
“One ounce took off the bad smell entirely, and the spirit became clear in a fortnight.
“ With an ounce and a half the spirit became clear in eight days.
« With two ounces in six days.
“ With three ounces in five days, and with four ounces in twenty-four hours.
“ It is remarkable, that ardent spirits which have been completely purificd by means of charcoal, give out a fine odour exactly resembling that of peaches.
“ Empyreumatic oils, dissolved in a sufficient quantity of highly rectified spirit of wine, are entirely deprived of their colour and smell by charcoal.” Crell. · Monsieur Cadet Devaux, a French chymist, “ has used the powdered charcoal for the removal of that peculiar flavour of West India molasses, so as to use it for sugar.” I could enume. rate various uses to which charcoal powder has been applied, but I am sensible of having intruded on your pages; it is sufficient to show, that the discovery was not reserved for any of my country. men.
TRAVELS IN FRANCE-FOR THE PORT FOLIO.
WE sometimes met with persons who had served in America during our revolutionary war, and heard a great deal of the melancholy fate of others. D’Estaigne, Custine, and Dillon terminated their days at the guillotine, and the end of the marquis de la Ronarie, whom we knew by the name of Armand, though more obscure, was not less calamitous: like others of his rank he had carried back with him to France ideas of civil and political liberty, or at least a zeal for some (perhaps not well defined or well understood) improvement in the government which contributed to the troubles of '89; but he soon afterwards regretted the part that he had taken, entered into a correspondence with the exiled princes, and was the great spring of that fermentation which showed itself at no early period in Brittany, and ended in what is called the war of the Chouans: the whole history of this extraordinary man might well deserve the pen of some good writer; his early attachment in Paris to a dancer of the opera, who had too much honour, too much respect for the noble family of her lover, to consent to marry him; his attempt to poison himself, his life of penitence and mortification at La Trappe, where he was discovered by accident, his flight to America, his services there, his return to France, and the subsequent events which partake equally of romance, and tragedy, might form the subject of a very interesting volume. Disappointed in