between the two brushes FF, in drawing fig. 2, is about four inches. The wooden tubes D, (which are about one inch in diameter,) through which the rope passes, should not be too long; the shortest next the brush should not exceed fifteen inches. They should gradually increase in length as they recede from the brush to the bottom, where they should not exceed thirty inches. The brush, fig. 3, is a good deal similar to a bottle brush, the handle about four feet long, made of whalebone, wrapped with iron or brass wire, the brush part made of bristles only. It will be found to be very useful in cleaning short flues, &c. in kitchen chimneys. Fig. 4 is a kind of tent, within which the machine may Contrivance for be worked. It will be found useful in rooms, where it is preventing the soot from flying particularly desirable, to prevent the least particle of soot into the room. from escaping. The cross bars E are of oak, about one inch and a half broad, and half an inch thick, turning upon an iron-pin at f. GG are two small iron rods, slipping upon pegs at h, to each of which is suspended a linen curtain, the one next the chimney, H, a short one, the other, as shown by the dotted line I, a long one, reaching to and resting five or six inches upon the floor. ee are small pegs, which, when the bars E are closed, fit into the notches gg, so as to stop the bars in the proper place, and prevent their being opened the wrong way. When the bars E are opened, they stretch the tapes K, which are fastened to the tops of the bars h, and are about three feet six inches long, to which extent only they suffer the 'bars to open. When thus extended, and placed in the proper situation, a loose sheet, of the same kind of linen as the curtains, is thrown over, and hangs down over the tapes, and upon the floor at each end, buttoning to the curtains at the corners, so as to form a complete tent, about five feet long, four feet wide, and five feet high, within which both the man and the boy can stand with the ma. chine to work it. VI. Abstract VI. Abstract of a Paper on the bitter Substances formed by the acid on indigo § I. 1. BEFORE I recite my experiments on the bitter Action of nitric and acid substances, that are obtained by treating indigo examined. with nitric acid, I will briefly advert to the labours of others on the same subject at different periods. 2. Mr. Haussman was the first, who made known the for- Amer from it, mation of the bitter principle by the action of nitric acid on indigo. Mr. Welther afterward obtained it from silk by and from silk. means of the same acid, described its principal properties, and gave it the name of amer. 3. Messrs. Proust, Fourcroy, and Vauquelin, have shown Almost all in several papers, that almost all organic substances, into organic substances yield it, the composition of which nitrogen enters, yield Welther's and frequently amer, and frequently benzoic acid. benzoic acid. Messrs. Fourcroy and Vauquelin studied with great at- Properties' of tention the properties of the amer obtained with indigo. to Fourcroy and amer according They observed, that it was acid; and that it was to be con- Vauquelin. sidered as a superoxigenated hydrocarburet of nitrogen, forming with pure potash a detonating compound, which appeared not to contain any nitric acid, as Welther had said. They observed farther, that, if the action of the nitric acid on the indigo was stopped, before the whole of the amer was formed, an acid was obtained, which sublimed in white acicular crystals, and appeared much to resemble benzoic acid. artificial tannin. 4. Mr. Hatchett, in his learned researches concerning the Mr. Hatchett's action of sulphuric and nitric acids on vegetable compounds, made known several products, that precipitate gelatine as tannin does: and on account of this property, combined with several others, he called them artificial tanning matter. 5. I observed in the year 1808, that the extract of Brazil wood was converted by nitric acid into a bitter substance, * Ann. de Chim. vol. lxxii, p. 113. Read to the National Institute, the 30th of Nov., 1809. that Action of nitric acid on brazil, and on aloes. Supposed acid from indigo. Inquiry instituted concerning it. Indigo treated that differed from the amer of Welther: and considered it as a compound of nitric acid, amer, and artificial tannin. 6. Mr. Braconnot, in a paper on gum-resins, speaks of an acid, which he obtained with aloes and nitric acid. He remarked, that this acid bore some analogy to the amer of indigo, and also to an orange-coloured substance, that Messrs. Fourcroy and Vauquelin had formed with muscular flesh and nitric acid*. 7. In the month of January, 1809, I resumed my examination of the amer of Brazil wood, in order to find how far it resembled the aloetic acid of Mr. Braconnot, when Mr. Vauquelin communicated to me a letter, in which he was informed, that Mr. Moretti, professor of chemistry at Udina, had obtained, by distilling indigo with nitric acid, an acid, that formed a detonating compound with potash, soda, the oxides of iron, lead, silver, &c. It was added, that Mr. Moretti considered it as a new acid, because it could not be confounded with the benzoic, which Messrs. Fourcroy and Vauquelin said they had formed with indigo. Mr. Vauquelin was desirous, that I should repeat these experiments; and at the same time requested me to examine, whether these acid and detonating products did not owe their properties to some nitric acid, which they retained in combination. § II. 8. Into a retort I poured four parts of nitric acid with nitric acid. at 32° [1-283] diluted with four parts of water. A receiver being fitted to it, I placed it on a moderately warm sand heat, and added gradually two parts of Guatimala indigo coarsely pounded. The mixture grew hot, and a quantity of nitrous vapours, carbonic acid, &c., was evolved. Fearing the action would become too violent, I removed the apparatus to a cold sand bath, and left the substances to themselves for four and twenty hours. Products distilled over. Matter in the retort. 9. During this time nitric acid, prussic acid, and a small quantity of yellow bitter matter, had passed into the re ceiver. 10. The liquor, that remained in the retort, was of a reddish yellow, and two concrete substances floated on it. * See Journal, vol. xxvii, p. 361. The most abundant had the appearance of a resin. The other was of an orange-colour, and disseminated in this in the form of clots. These were both separated from the liquid, washed with cold water, and then boiled. The resinous matter congealed on cooling; and the orange-coloured substance, after having dissolved, fell to the bottom in small grains, which did not adhere to each other. acid. 11. The water, that had been employed to separate these The liquid two substances, was added to the liquor (10) left in the distilled. retort, and then distilled. Nitric acid, prussic acid, amer, Products. and a little ammonia, passed into the receiver. The con- Yielded crystals centrated liquor on cooling let fall crystals formed of the of amer and a amer of Welther, and of the benzoic acid of Messrs. Fourcroy and Vauquelin. Having dissolved these in hot water, I obtained by cooling the crystallized acid, retaining a little amer; and by evaporating the liquid fine yellow scales of amer. the mother 12. The liquid, which had furnished the crystals (11) of Fat oil from amer and acid, after boiling down let fall a red liquid sub- water. stance resembling a fat oil. lime. 13. The supernatant liquor (12) was evaporated to dry-More of this, ness, and hot water poured on the residuum. Oxalate of and oxalate of lime was left undissolved; and the water, on cooling, let fall some oily matter, and afterward a yellow sediment, which was pretty soft, and differed from the oily matter only in the proportion of its principles. examined. 14. I shall now proceed to examine, 1st the amer; 2d, The products the acid substance, which has been compared to benzoic acid; 34, the resin. The other products being only compounds of these three, I shall not speak of them under separate heads; but I intend in a future paper to return to the substance of an oily appearance. § III. Art 1. Of the Amer. 15. The scales of amer, which I mentioned (11), re- The amer imtained a little resin, whence they derived a deep yellow pure. colour; and a small quantity of the acid, which has been called the benzoic, but which I shall designate under the name of volatile acid. SUPPLEMENT.-VOL. XXX, A a When Its properties when pure. Action of heat on it. Apparatus for examining its products. Heat applied. Gaseous products. prussic acids. When the amer is very pure, it is white inclining to straw-colour. Its solution in water is not reddened by salts of iron at a maximum. That which was employed in the following experiments had been boiled in nitric acid: afterward crystalized repeatedly; combined with potash, and then separated from it by muriatic acid; and lastly crystallized, till, when redissolved in water, it no longer precipitated solution of silver. 16. The amer, being gently heated in a common phial, sublimed in little needles, or scales, of a white colour inclining to straw-yellow. Thrown on a redhot iron it took fire, and left a coal, which melted. If exposed to a red heat in a retort, a pretty strong smell of nitrous acid and of prussic acid is evolved. To examine the products of the amer subjected to the action of heat, I contrived an apparatus consisting of a glass ball surmounted with a tube, which terminated under a jar filled with mercury. Into the ball I introduced 2 dec. [3 grs.] of amer, more would have burst it, and fastened the tube to the jar by means of a wire. 17. When the apparatus was thus arranged, I heated the ball with a redhot coal: the amer melted, grew black, and took fire; a light coal remained; and aqueous vapour, gas, and a little charcoal passed into the receiver. The gaseous product reddened litmus paper. It had the smell of nitrous acid, mixed with that of prussic; and I analysed it in the following mode. I first passed some water into the jar, and a slight absorption took place. Carbonic and When this appeared to be at an end, I shifted the water to another jar filled with mercury; and found, that it had dissolved a portion of amer, which had been volatilized without decomposition, some carbonic acid, and some Mode of detect-prussic acid. To detect the latter it was necessary, to saing the latter. turate the liquid with carbonate of potash; and pour it into a small glass retort adapted to a receiver, in which were some threads twisted together, impregnated with green sulphate of iron, and afterward dipped in a weak solution of potash. On distilling, water and prussic acid passed over; and the thread, after having been washed with weak muriatic acid, became blue. (If sulphate of iron were |
