hardly was it discovered when I employed it in experiments of shooting, the success of which encouraged me to continue them. Accepting the obliging invitation which I received, I went, in the middle of April, to Wurtemburg, and made experiments with gun cotton, both in the arsenal of Ludwigsburg, in the presence of artillery officers, and in Stuttgard, before the king himself. In the course of May, June and July, with the kind cooperation of the Commandant de Mechel, of M. Burkhardt, captain of artillery, and other officers, I subsequently made, in this city, (Bale,) numerous experiments with arms of small calibre, such as pistols, carbines, &c., and afterwards with mortars and cannon-experiments at which Baron de Krüdener, the Russian ambassador, was several times present. I may be allowed to mention, that I was the person who fired the first cannon loaded with gun cotton and shot, on the 28th of July, if I remember aright, after we had previously ascertained, by experiments with mortars, that the substance in question was capable of being used with pieces of large calibre.

About the same time, and indeed previously, I employed gun cotton to blast some rocks at Istein, in the Grand Duchy of Baden, and to blow up some old walls at Bâle; and in both cases I had opportunities of convincing myself, in the most satisfactory manner, of the superiority of this new ex plosive substance over common gunpowder.

Experiments of this kind, which took place frequently and in the presence of a great number of persons, could not long remain unknown; and the public journals soon gave, without participation on my part, descriptions, more or less accurate, of the results which I had obtained. This circumstance, joined to the short notice which I inserted in the May number of Poggendorff's Annalen, could not fail to attract the attention of German chemists: in the middle of August I received from M. Boettger, professor at Frankfort, the news that he had succeeded in preparing gun cotton and other substances. Our two names thus became associated in the discovery of the substance in question. To M. Boettger the gun cotton must have been particularly interesting, as he had previously discovered an organic acid. which deflagrates readily.

In the month of August I went to England, where, assisted by the able. engineer, Mr. Richard Taylor of Falmouth, I made numerous experiments in the mines of Cornwall, which were entirely successful, in the opinion of all competent witnesses. Experiments on the action of gun-cotton were also made in several parts of England, under my direction, both with small fire-arms and with pieces of artillery, and the results obtained were very satisfactory.

Until that time there had been little or nothing said of gun-cotton in France; and it will appear that the short notices which Mr. Grove gave at Southampton at the meeting of the British Association, and the experiments with which he accompanied them, served first to attract the attention of French chemists to this substance.

At Paris, the thing was at first considered hardly credible, and jokes even were passed upon it; but when there could no longer remain any doubt as to the reality of the discovery, and when several chemists in Germany and other countries had published the processes which they employed to prepare the gun cotton, then a lively interest was manifested in a subject which had

In the month of June, I made also the first percussion caps, and employed them with success for muskets, in the presence of the above-mentioned officers.

just before excited derision, and it was soon pretended that the new explosive substance was an old French discovery. It was declared to be nothing more than the xyloidine first discovered by M. Braconnot, and afterwards investigated anew by M. Pelouze, and the only merit left me was to have conceived the happy idea of putting this substance into a gun-barrel. The knowledge of the composition of xyloidine ought to have sufficed to convince those who put forward that opinion, that it is not suited for fire-arms, on account of its containing too much carbon and too little oxygen for the chief part to be converted into gaseous matters during the combustion. It was moreover very easy to discover the essential differences between the xyloidine of Braconnot and gun cotton. Nevertheless the error was kept up for some months.

Matters stood thus, when, on the 4th of last November, a Scotch chemist, Mr. Crum, of Glasgow, published a memoir, in which he showed that guncotton is not the same product as xyloidine, but that it presents an essentially different composition; and towards the end of the same month, the French Academy received a communication of the same nature. The gun cotton was then no longer xylonline; it was called pyroxyloidine, and the first was admitted to be unsuitable for fire-arms.

If, therefore, it is proved that from the commencement of 1846, I prepared -gun cotton and applied it to the discharge of fire-arms and that M. Boettger did the same in the month of August,-if it be admitted that xyloidine cannot serve the same purposes as this cotton, and if it be notoriously known that what is now called pyroxyloidine was not brought before the French Academy and the scientific world until towards the middle of last November, the idea of attributing to France the discovery of gun-cotton cannot be seriously entertained, or of assigning to me merely a practical application of that which another had discovered.

I appeal to the justice of Frenchmen, to decide the point to whom belongs the honor of not only being the first to apply the new substance in question, but also of having first prepared it to M. M. Braconnot and Pelouze, or myself. I must, moreover, add expressly, that it was not xyloidine even which led to my discovery, however intimate may be its relation with gun cotton; it was theoretical ideas, possibly very erroneous ones, but which are peculiarly my own, as well as some facts which I was also the first to discover.

Suum cuique is a principle of morality on which society at large rests; why should it not be strictly respected in the republic of science? M. Pelouze is a distinguished chemist, and already possesses a sufficiently high reputation not to require to elevate his pretensions on the merits of others; and I am fully persuaded that this estimable chemist, of well known truth of character, will, appreciating with impartiality the circumstances which have occurred, freely render ine the justice to which I consider myself entitled. Bâle, Dec. 28, 1846.

The above article from Professor Schönbein was first published in the Archives des Sciences Physique et Naturelles.

Microscopic Examination of Gun Cotton; by Dr. Bacon, (Proc. Boston Soc. Nat. Hist., Feb. 1847, p. 195.)

Specimens of the cotton, before and after preparation, were put up in Canada balsam, on slips of glass, and covered by very thin glass. When viewed by transinitted light, with powers from 150 to 800, many of the fibres of the gun cotton appear thickened, but no other change can be perceived in comparison with the unprepared article. There is no appreciable difference in the transparency of the two.

They were now examined in polarized light by means of the polarizing attachment to the microscope. When the polarizing and analyzing prisms are so arranged as to afford a dark field, the riband-like fibres of the cotton before preparation are seen as luminous objects upon a black ground, and are tinged with bright and varied colors. They are thus proved to possess a strong polarizing power.

The gun cotton, under the same circumstances, presents an entirely dif ferent appearance. Its fibres are much less luminous, and have a nearly uniform dull blue color. It is evident that the process of preparation has so altered the structure of the fibres as to lessen very greatly their action on polarized light.

Gun cotton prepared by Dr. Jackson by immersion for twelve and for eighteen hours in the strongest acids, has not lost its polarizing power in any appreciably greater degree than after an immersion of three minutes only. This agrees with the results of other modes of trial in indicating that the latter period is sufficient for the complete preparation of the cotton when the acids are of full strength. In all the specimens there are some filaments so nearly destitute of polarizing power as to be nearly invisible on the black ground, but none have been found entirely without action. When the polarizing and analyzing prisms are in such a position as to give a bright field, a portion of the fibres become tinged with a color approaching to orange, while the remainder appear colorless, as in ordinary light,

Purifying Liquids by Galvanism.-A patent has been granted for an interesting process by which a feeble galvanic power is employed to separate salts, acids or alkalies from water or other liquids. Two porous vessels containing water are partly immersed in the liquid to be purified, and a zinc plate placed in one vessel and an iron plate in the other vessel. Other metals would answer, but the inventor prefers the above. The zinc and copper plate being connected by a wire, galvanic action is established, and the salts or other soluble matters are carried through into the porous cups, and these accumulate in one or the other according to the electrical relations of the impurities.

Lubricating Compounds.—A patent has been granted for a lubricating compound, which is represented to be already in extensive use for rail-car axles. Six parts by weight of whale oil are mixed with one part of asphaltum and heated gradually to 500° or 600° Fahrenheit, and then two parts of coal tar are added, stirring the mixtuee until the materials are incorporated. It is alleged to be a cheap and economical liquid and does not stiffen in cold weather, or agglutinate from use.

CALORIFIC.

Patents granted, 35.

Stoves. This class of inventions has multiplied upon the office much above any other, and although the subject is in itself easy of comprehension, yet the examination for letters patent for a cooking stove is frequently attended with more difficulty and nice discrimination than would arise from an invention of a complicated character. Quite a number of patents have been granted for stoves, all presenting novelty of arrangement or combination, and yet it is difficult to select from among them all any one feature of decided interest.

A useful article of foot-stove has been patented, consisting of a vessel

to be filled with hot water and surrounded with non-conducting material, and provided with an opening large enough to receive the feet and entirely cover them with a heating surface. In the ordinary foot-stoves the feet are warmed only from below, while the stove in question warms the feet above, and on the sides, as well as below.

An improvement in the boilers of cooking stoves has been patented, and although a most simple device, it is one which appears to have been much needed. Every one using a cooking stove must be aware of the difficulty and expense of boiling water in the largest size boilers. A portion only of the bottom being within the flue of the stove exposed to the fire, while the whole surface of the upper part is exposed to the air, it requires a large amount of fuel to raise the temperature of the water to the boiling point and maintain it for any length of time. This difficulty has been to a considerable extent removed by inclosing the boiler with a casing which is open at the bottom where it rests upon the stove, and allows the fire or the products of combustion to rise between the boiler and casing, and thus economizes much heat. A jacket around a boiler above a stove, merely to serve as a non-conductor, is an old device, but the novelty in this case consists in making this jacket to communicate with the flue of the stove, rendering it unnecessary to carry the bottom of the boiler far into the flue.

Heating Wheel Tires.-A patent has been granted for a furnace of peculiar construction, which, it is alleged, will heat the tire much sooner and with less fuel than the ordinary way of heating upon the ground in the open air. It is a circular furnace, made up of separate sections for the sake of portability, and may be used in or out of doors.

Drying Grain and Flour.-The subject of kiln drying grain is one of increasing importance, in view of the increasing exportation of that article. It is often remarked, that corn meal bread made at the North of Southern corn, differs essentially from that made at the South. It is doubtless to a considerable extent true, and the difference is not entirely due to the operation of transporting, but in a great measure to inattention to the proper drying of the grain. A greater number of applications for letters patent for corn kilns has been made during the past year than probably ever before within the same space of time. Several patents have been granted, but the principles of drying and heating have so long been well understood in their application to other materials that little else of novelty has been introduced than in the mechanical contrivances to suit the change of material.

Ventilators, or Chimney Caps.-The subject of smoky chimneys is one of so much moment and interest as to engage and invoke the attention of men of science, and involves the most important considerations of economy of fuel, personal comfort and health. Few subjects have been essayed by a greater variety and multiplicity of experiments than the curing of smoky chimneys, and yet there is wanting a practical manual upon this subject, which should provide remedies for the numerous contingencies. From a survey of facts it must be obvious that there can be no universal rule of construction and operation, and that in providing remedies they should be adapted to the varied circumstances of building and locality. This complication of the conditions renders the aid of science very necessary, and the subject at times has received attention from the British Association.

Several patents have been granted for chimney caps professing superiority over other known forms in improving the draft of chimneys. There are mainly three classes of chimney caps for the prevention of smoke. The

first is a moveable cap which by a vane is made to turn in such manner as to have the exit of the smoke in the direction of the wind.

The second class is the cap in which, from peculiarity of form, the draft is increased by the tendency to produce a vacuum at the mouth of the exit pipe. Under this class the varieties of form are very numerous. The third class is one in which the cap revolves by the action of the wind, and this, operating to revolve a fan or spiral within the chimney flue, raises the smoke aechanically.

The caps of the first and third class generally obstruct the draft when they do not readily obey the action of the wind, which, from undue friction, and rusting of the axles or spindles upon which they turn, is too frequently

the case.

Of the second class, two forms have been patented, termed the injecting and ejecting ventilator. The first is the reverse of the second in operation, and at first sight was so considered in its construction. Both forms. were, upon the first examination, decided to be wanting in novelty, or so closely resembling other known forms as to present no distinctive feature. The cases, however, were open for explanation, and this was furnished in the most satisfactory manner by actual demonstration. As a mere change of form is not the subject of letters patent, and as in this class of inventions the value of the cap depends upon peculiarity of form and a slight difference in form sometimes makes a great difference in the result, a practical illustration is of great value in testing the question of novelty. The patentee of the past named ventilator, exhibited by complete experimental trials with an extensive apparatus, the full value and operation of his ventilator, and demonstrated in a conclusive manner the difference between his own invention and those to which he had been referred as presenting similarity. The principal features of the ejecting ventilator are, a conic frustum mounted upon a tube of some length, and a plate or fender supported at some distance above the flue or opening in the conic frustum. The diameter of the opening through the tube and conic frustum is the same as the diameter of the chimney flue. The cap is secured permanently upon the chimney and according to the experiments performed here, gives a strong upward draft, whatever may be the direction of the wind.

The injecting ventilator consists of a number of inverted conic frusta, so arranged that a current of air from any quarter, blowing upon the cap, causes a strong downward draft. The two ventilators are designed for combined, as well as separate use. The inventor contemplates their general application to ships, steamboats, crowded rooms, and, indeed, to all cases where ventilation is necessary. The experiment has been tried on ship-board with success. The injecting ventilator supplying the hold with air, and the ejecting carrying it rapidly out; and thus by a current of air in one direction these caps are made to co-operate, and must be more effica cious than the many contrivances for merely forcing air into the hold.

The inventor represents that one cap may be made to cover any number of flues in a chimney, and that in one instance, a chimney containing 14. flues, was surmounted by a large cap and the draft in all the flues made perfect. This invention has been submitted to the rigid scrutiny and received the approbation of the American Academy of Science and Art.

The inventor asserts that he has found but one condition under which the ejecting ventilator will not act to raise a draft. This condition can never occur when the cap is upon a chimney, and perhaps might never be