On page 167, we quoted from Mr. Nursey's paper on the above subject, read before the Society of Engineers, of London. The facts therein stated are so valuable for reference, and withal so interesting, that we continue our extracts. Mr. Nursey describes, by the aid of an engraving, a simple apparatus for determining the ignition point of explosives, by which their absolute and relative temperatures are ascertained at the instant of explosion. It is simply a contrivance similar to a portable retort stand. An upright fixed in a weighted base, to stand upon a bench or table, sustains two transverse adjustable sliding bars, secured at any point desired by set screws. From the upper one depends a thermometer graduated to 650 Fah. The lower arm holds a cup of oil into which the bulb of the thermometer dips. A miniature cup containing a small quantity of the explosive mixture, floats on the surface of the oil. Heat is applied by a gas jet under the oil bath, or by a spirit lamp. By this apparatus, Mr. Horsley has ascertained the ignition point of various explosives, and the following are among some of his results: Gunpowder ignites at a temperature of 600 Fah. A sample of Horsley's powder gave 480 as the ignition point. Gun cotton of a powerful character, prepared by Horsley, ignited at 825 , while some of Prentice's sporting gun cotton exploded at 410 . Trials of Schultzens sporting powder gave 885 as the ignition point. It is as well, at a time like the present, when new explosive compounds are constantly being brought under notice, that experimenters should know the character of the material they are dealing with, and which they will be enabled to ascertain by means of the above simple apparatus. Another, and perhaps safer, application of chlorate of potash to the purpose in question was made some nine years since by M. Hochst dter, a German chemist. Unsized paper was thoroughly soaked in, and coated with, a thin paste consisting of chlorate of potash, finely-divided charcoal, a small quantity of sulphide of antimony, and a little starch, gum, or some similar binding material, water being used as the solvent and mixing agent. The paper was rolled up very compactly and dried in that form. In this manner, very firm rolls of an explosive material are obtained, which burns with considerable violence in open air, and the propelling effect of which, in small arms, has occasionally been found greater than that of a corresponding charge of rifle powder. Moreover, the material, if submitted in small portions to violent percussion, exhibits but little tendency to detonation. But,as no reliance can be placed on a sufficient uniformity of action, in a firearm,of these explosive rolls, this alone sufficed to prevent their competing with gunpowder. The same description of explosive preparation, differing only from that of M. Hochst dter in a trifling modification of its composition, was again brought before the public in this country in the early part of 1888, having1 been patented by M. Reichen. The author has used this gun paper with very good results in rifle shooting, but nothing practical appears to have been done with the material. The mixture previously referred to as German, or white gunpowder, consists of chlorate of potash, ferrocyanide of potassium, and sugar. Many years since it was proposed and tried without success as a substitute for gunpowder. Since then various preparations of similar character have been suggested for employment, either as blasting and mining agents, or for use in shells, or even for all the purposes to which gunpowder is applied. The most recent of these mixtures with which the author is acquainted, is a white gunpowder made by H. W. Reveley, of Reading. This mixture is a perfectly white impalpable powder resembling flour, powdered chalk, or magnesia in appearance. Reveley recently informed the author that he lias constantly made and used It in preference to the ordinary gunpowder, both on account of its superior propelling power which is at least one-third greater and its perfect cleanliness. It produces neither smoke nor flash of flame at the muzzle on discharge, and can be used in a casemate with perfect comfort to the gunners. Mr. Reveley has used it for every purpose to which ordinary gunpowder is applicable, and invariably with the most perfect success. He has made many parcels of the white gunpowder during the last ten years, and has always found them uniform, both as regards strength and other properties, and he has never met with the slightest accident, although he has tested it very severely. The composition of white gunpowder is as follows: Chlorate of potash........................ 48 Yellow prussiate ditto..................... 29 Finest loaf sugar. .'....................... 23 Parts by weight...................... 100 . In manufacturing this powder the yellow prussiate is dried in an iron ladle until it is as white as the chlorate. The ingredients are ground separately to very fine powder, and are then mixed by means of a conical sieve until they are thoroughly incorporated, but not by trituration. For small quantities, Reveley uses a common Wedgewood mortar and pestle, which must be perfectly dry and clean. The operation does not take many minutes, and with the above precautions, its manufacture is free from danger. In loading, it is treated in the same way as ordinary gunpowder, being pressed down by hand solid, but not hard. The charge is ignited in the usual way, with a common cap and nipple. In actual use, it does not appear to possess a bursting so much as a propulsive power, and Mr. Reveley has obtained some of the highest penetrative results in his rifle practice with it. The economy of this powder will at once be apparent, when it is stated that its wholesale cost is about 86s. per cwt., but as its strength is at least one-third greater than that of ordinary powder, its cost may be comparatively estimated at about 60s. per cwt. One important feature in the manufacture of white gunpowder is that it does not require to be indeed, it cannot be granulated, which process is the great source of danger in powder mills. The universal use of the cartridge entirely obviates any objection that may be made to white gunpowder on that score, or en the score of similarity in appearance to other substances, and, owing to its compact form, it only occupies half the usual space. Beside the foregoing, there have been several cruder applications of chlorate of potash in the production of explosive compounds, which it is unnecessary here to notice more particularly. Among other materials, wood has been pressed into service to aid in superseding gunpowder as a practical explosive. Soon after Schonbein's discovery of gun cotton, a Prussian artillery officer, Captain Schultze, while investigating the subject, conceived that a finely divided wood could be converted into a controllable explosive agent more readily than cotton. He produced the substance known as gun sawdust,the explosive properties of which are mainly due to its impregnation with a large proportion of an oxidizing agent. In preparing the gun sawdust, the wood is purified from all resinous substances, and is digested in a mixture of sulphuric and nitric acids. This gives a very feeble explosive material, which is further strengthened for ultimate use by impregnation with nitrates, by which it is made to acquire great explosive power. Here, then, is a powder which may be preserved in a comparatively harmless condition until required for use, when it may be rendered powerfully explosive by impregnation with the nitrates. Although its properties are somewhat similar to those of gun cotton, many of the advantages of which it possesses, it is open to one very fatal objection. To be within the limits of safety, the completion of its manufacture must be delayed until the moment it is required for use ; and, moreover, the final ingredients are the most dangerous, and require refined manipulation. It is needless to point out how incompatible the conducting this completing process is with the ordinary details of mining; the care and nicety required in such a chemical operation, must be referred to the skilled operator, and not trusted to the rough-and-ready hand of the miner. Practical safety can only be attained by an explosive agent into which the stray spark may fall without producing more than a gush of flame, a gradual burning, or without causing ignition at all, but which, nevertheless, when properly rammed home and tamped, may be fired with results at least equal, if not superior to ordinary gunpowder. Utilisation of High Falls of Water. Glynn's " Power of Water," contains the following in regard to the utilization of high falls of water: " Attempts have been made to employ a high fal! of water by placing one wheel above another; this was tried many years ago at Aberdare, in South Wales, where two wheels, each forty feet in diameter, were so placed, like the figure of 8, and were connected by teeth on their respective rims the lower wheel receiving the water after it left the upper one, and revolving in the opposite or reverse way. The result was not satisfactory ; but in another case, a drawing of which lies before the writer, wherein Messrs, Charles Wood and Brothers, of Macclesfield, had two overshot water wheels, each of twenty-six feet in diameter, and six feet wide, placed over each other, they succeeded in a somewhat different arrangement of the toothed-wheel work. The two wheels were not connected immediately with each other, but by means of pinions, which j worked into teeth upon the rims of the two water wheels, causing them both to revolve in the same direction, so that the water, on leaving the buckets of the upper wheel, was more easily and readily received by the buckets of the lower wheel. " In either of these cases, however, the employment of the turbine, or the pressure engine, would have been much less costly and more effective. The like may be said of all the contrivances to substitute endless chains with buckets applied to high falls instead of water wheels. " Where the quantity of water is large and variable, and the fall such as may be termed an intermediate hight, but varying also with the supply, it is found advantageous not to lay the water upon the top of the wheel, so that it may work overshot, but to make the diameter of the wheel greater than the mean hight of the fall, and to lay the water, as it were, 'on the shoulder' of the wheel, or at forty-five degrees from the perpendicular; that is, half way between the horizontal line and the perpendicular, or, as millwrights say,' at nine o'clock.* Very little mechanical effect is produced in the upper eighth of the circle as compared with the nex quarter, on which the descent of the water is nearly perpendicular, and when the wheel is fitted with toothed segments at or near its circumference, acting on a pinion placed on a level with the axle, the weight of the water is brought to bear at once upon the pinion teeth, the stress is taken off the arms of the wheel, and the axle becomes, as it were, merely a pivot on which the wheel turns. By this arrangement, the late Messrs. Hughes and Wren, of Manchester, were enabled to make the arms of their wheels of simple tension rods of bar iron, by which the rim of the wheel was tied and braced to the center, a plan which, with some modifications and improvements, is still in use, and sometimes the segments have interior teeth, which render the wheel-work more compact. " In the best constructed wheels, the water is laid on in a thin sheet of no greater depth than will give it a somewhat greater velocity than that of the wheel, the difference being just sufficient to pour into the succeeding buckets the proper supply of water. The buckets should be so capacious that they need not be full when the wheel carries its maximum load, in order that no water may be wasted, and that they may retain the water in them till the last moment that its weight on the wheel is effective, and yet empty themselves as soon as it ceases to be so. It is also expedient in practice to make the width of the sheet of waer less than that of the wheels ; if the wheel be broad on the face, the stream maybe four inches shorter than the length of the buckets ; the air escaping at the ends is thus prevented from blowing out the water ; and all these precautions, though small in themselves, tend to produce smoothness, regularity, and increased effect in the working of the machinery. " There is, however, one mode of using water power acting by its gravity in buckets upon a chain, much employed in South Wales, which is found very useful in raising ore from the pits. An endless chain is passed over a wheel of six-teen feet in diameter, placed between two shafts. The chain passing down each shaft, and through an opening at the bottom between the two, two large buckets, or rather shallow tubs of wrought iron, are fixed upon the chain, so that the suspension is by the center of the tubs, and they are so placed that when one tub is at the top of its shaft, the other is at the bottom of its shaft. Each tub or bucket is covered by a strong platform, whicli fills and closes the pit's mouth when hoisted up, and carries the small wagon or tram containing the ore upon it; and each is also fitted with a valve at the bottom to discharge the water. A branched pipe, communicating with an elevated reservoir, is laid to the mouths of the shafts, and fitted with stop-cocks or valves. The tub at the surface being filled with water, overbalances the empty tub at the bottom, and raises it, with its tram load of ore, to the top. When the full bucket has descended the shaft, the valve is opened and the water discharged; the other being filled in like manner, descends, and thus alternately each raises the other with its load of oar. The water finds its way out of the mine by a drift or adit into the valley ; the long loop or bight of slack chain below the buckets, and hanging to the center of each, equalizes the weight of chain at all times ; and -a brake applied to the large wheel regulates the speed of the descending bucket. In some places the two buckets work in one shaft of an oblong form; the diameter of the wheel is re duced to seven feet; it is fitted with toothed segments, working into a pinion, fixed upon a second axle, on which the brake wheel is placed, in order to gain the requisite power to control the descending weight. Drawings of both these plans lie before the writer, but the principle and construction are so simple that a description will probably suffice. It may be proper to mention that the buckets generally work in guides, that the discharging valves are opened by striking upon a point or projecting spike at the bottom of the shaft, and that upon the platforms which cover the buckets, there is a portion of the rail or tramway laid to match with the lines of way at the top and bottom of the shaft, so that the tram or carriage may run from the platform to its destination." Dr. Mallet's Opinion of tlie Heaton' Process. The following is Dr. Mallet's opinion of the reality and commercial value of Heaton's process : " This process for converting crude pig iron into wrought iron and into steel, by the employment of nitrate of soda in Heaton's patent converter, has been repeated at Langley Mills many times in my presence. I have examined minutely into its details as applicable in practice on a large scale, and its results; and I have also considered the chemical researches made as to the materials used and products obtained, by Professor Miller, of King's College, and I have been present at, i experiments, conducted by Mr. David Kirkaldy, at his Testing Works, at Southwark, as to the physical qualities of the products which were obtained by this process, in my own presence, at Langley Mills. In view of all the facts that have come before me, I can affirm the following as truths established beyond question: " 1st. That Heaton's patent process of conversion by means of nitrate of soda, is at all points in perfect accord with metal-lurgic theory. That it can be conducted upon the great scale with perfect safety, uniformity, and facility, and that it yields products of very high commercial value. " 2d. That in point of manufacturing economy or cost it can compete with advantage against every other known process for the production of wrought iron and steel from pig iron. " 3d. Among its strong points, however, apart from and over and above any mere economy in the cost of production are these: It enables first-class wrought iron and excellent steel to be produced from coarse, low priced brands of crude pig iron, rich in phosphorus and sulphur, from which no other known process, not even Bessemer's, enables steel of commercial value to be produced at all, nor wrought iron, except such as is more or less either " cold short" or " red short." Thus, wrought iron and cast steel of very high qualities have been produced, in my presence, from Cleveland and Northamptonshire pig irons rich in phosphorus and sulphur, and every iron master, I presume, knows that first-class wrought iron has not previously been produced from pig iron of either of these districts, nor marketable steel from them at all. " Heaton's process presents, therefore, an almost measureless future field in extending the manufacture of high class wrought iron and excellent steel into the great iron districts, as yet precluded from the production of such materials by the inferior nature of their raw products. It admits of the steel manufacture also being extended into districts and countries where fuel is so scarce and dear that it is otherwise impossible. " I cannot, in this brief communication, point out the prospects which the employment of this system presents, of greatly diminishing the existing waste of material, fuel, time, and wages, in the puddling process, and of lessening difficulties in relation to labor questions which beset that process, injuriously to the British iron trade. Nor can I adequately point out the large reduction in the original outlay for plant which this system admits of as compared with any other for equal annual out-put of iron and steel. " Dr. Miller has proved, incontrovertibly, that the Heaton process does eliminate from the crude pig iron almost the whole of the phosphorus and sulphur, the trace remaining being unobjectionable in the wrought iron and steel produced, even when they have been made from the pig irons known to be the richest in these injurious constituents of any make in Great Britain. " The wrought iron made in my presence from Cleveland and Northampton pigs, and tested for tensile resistance, also before me, bore a rupturing strain of twenty-three tuns per square inch, and an elongation of nearly one-fourth of the original unit in length. It is therefore iron of great strength and toughness, and yet probably by no means the very best that this process is capable of producing hereafter. It possesses those qualities which best fit iron for artillery, armor plates, and iron ships or boilers. " The tilted cast steel, also made in my presence, from the very same pig irons as the above, bore a tensile strain at rupture of above forty-two tuns per square inch with an elongation of one-twelfth of the unit of length. It is, therefore, a remarkably tough and fine quality of steel, well suited for rails, ship-building, and all other structural uses. In a word, steel suited for any purpose known to the arts can be* produced by this system from inferior brands of pig iron." -------------- The Electrieal Machine at Trinity College. It is not generally known, says the Hartford Times, that Trinity College in this city possesses what, if not the largest, is the most powerful electrical machine in this country. It was made in Vienna expressly for this college. We were present at an exhibition of the same, March 6th, and were as much pleased as we were astonished by the wonderful power of the machine. It occupies a space on the floor of about 4 J by 5-J- feet. The electricity is collected in large brass balls, supported by strong pillars of a peculiar glass, in which there is no metallic substance. The rubbers and the points upon which the axles of the plates work are also supported by the same kind of pillars. These balls are nine inches in diameter, having a smaller ball between them; and from a projecting point midway between the larger balls, the spark is drawn to a metallic surface mounted on glass. This is movable and connected with the rubber and the ground. The large balls are surmounted by two rings of light hollow wood, lined with metal which are thirty inches in diameter, and greatly increase the force of the spark. The whole apparatus, to the top of these rings is eight feet high. The plate is of heavy glass, very clear, 46 inches in diameter and three-eights of an inch thick. The operator stands at a safe distance, and the handle of the machine is insulated by means of a rod of glass. The rubbers are covered with Bunsen's amalgam and the electricity when generated is taken from the plate by sharp points and conveyed to the above mentioned bath. It is wonderful what an enormous amount of electricity can be obtained from this machine. A few revolutions of the wheel will cause a spark eight or ten inches long to fly off, and this length can be greatly increased by withdrawing the spark catcher, and pushing in the point from which the discharge takes place. The peculiar odor which attends the generation of electricity is perceptible in all parts of the room, and persons are affected while standing several feet from the machine. On that evening and the condition of the room, atmosphere, and other surroundings were not what they should have been for a perfect exhibition of the machine spark ten inches long was drawn twenty-one and a-half inches from the machine. Among the different experiments shown by Professor Brock-lesby, that evening, were, first, the charging and discharging of Lsyden jars, around the interior of which bits of tin foil, diamond shaped were placed. The electricity would run from one to the other, filling the jar with rows of light. Another jar was lined witli gold-leaf, and surrounded by brass filings. The electric fluid would run through this in lightning like streams. Tubes and globes similarly arranged were also shown. Then he showed the effect of electricity passing through vacuum. A hollow cylinder of glass, some five feet in length, was exhausted of air, and connected with the ma- chine, the electricity passing through in streams of a light violet color, resembling the " Northern Lights." Then the effect of electricity on different gases was shown by means of tubes filled with gases. When passing through that filled with nitrogen gas, a yellow light was seen in vertical streams alternately light and dark. In going through carbonic gas, a green light was obtained, while a pale halo seemed to surround the tube. Through hydrogen there was a continuous flow of blue and yellow light, but the prettiest experiment was when the machine was connected with a cylinder filled with a combination of gases. Inside this cylinder was an arrangement of glass coils. As the electric fluid passed through these it gave the appearance of a slender vase of brilliant green, filled with pink, olive, violet, and yellow flowers. Large Leyden jars were then filled, and by means of a discharging rod, the electricity was carried off, passing on its way through a piece of card board on to a chain and wire connecting with the ground. A small hole was pierced through the card. This discharge would be sufficient to knock a man senseless, if not to kill him. Other experiments were tried, shocks administered to those who wished, ajar broken our reporters hair made to stand on end " like quills upon a fretful porcupine," and an opportunity given to all to see the " long spark." The exhibition was an exceedingly interesting one, and we wish that Professor Brocklesby could be induced to repeat it in a larger hall, where our citizens might have an opportunity of witnessing the workings of the machine. --------------, .-------------- Solar Meat as a Motive Power. A shrt time since we briefly referred to the experiments of M. Mgfachot, made with a view to utilize solar heat as motive pow r. He, in a contribution to the Comptes Rendus, thus speaks of some of their results : According to my experiments, it is easy to collect, at a cheap rate, more than three-fifths of the solar heat arriving at the surface of the globe. The intensity of this calorific source, so feeble in appearance, was revealed by Pouillet, more than tafa~ ty years ago. At Paris, a surface of one square meter, normally exposed to the sun's rays, receives, at least, whatever may be the season, during the greater part of a fine day, ten heat units (calories) per minute. [The unit of heat adopted by most physicists is the quantity necessary to raise one pound of water from 0 to 1 C. We suppose M. Mouchot adopts the same standard.] To appreciate such an amount of heat, it is sufficient to observe that it will boil, in ten minutes, one liter of water, taken at the temperature of melting ice, and it is almost equal to the theoretical power of a one-horse steam engine. Under the same conditions, a superficies of one " are " (119*603 square yards) would receive, during ten hours of insolation, as much heat as results from the combustion of 120 kilogrammes (321,507 lbs. troy) of ordinary oil. These numbers are eloquent: they should, if not dispel, at least weaken the serious fears entertained by some, in consequence of the rapid exhaustion of coal mines, and the necessity of going to increasingly greater depths, disputing with the subterranean water this precious combustible. The intensity of the calorific radiation of the sun is, moreover, much less at Paris than in intertropical regions, or upon the elevated plains. It is, therefore, probable, that the invention of " sun-receivers " will, some day, enable industry to establish works in the desert, where the sky remains very clear for a long time, just as the hydraulic engines have enabled them to be established by the side of water courses. Although I have not been able to operate under very favorable circumstances, since my experiments have only been made with the sun ef Alengon, Tours, and Paris, I proved, as far back as 1861, the possibility of maintaining a hot-air engine in motion, with the help of the sun's rays. More lately I have succeeded in boiling, tolerably quickly several liters of water submitted to insolation. In short, having satisfied myself that it was sufficient to have a silver reflector, with a surface of one square meter, to vaporize, in a hundred minutes, one liter of water (0*88 quart), taken at the ordinary temperature, or, in other words, to produce seventeen liters of vapor a minute, I tried to work a small steam engine by solar heat, and my efforts were crowned with success in June, 1866. In the meantime I have been able, by very simple apparatus, to obtain some remarkable effects from insolation, such as the distillation of alcohol, the fusion of sulphur, perfect cooking of meat, bread, etc. None of these experiments, particularly the application of the sun's heat to machinery, have been tried upon a sufficiently large scale. It would, therefore, be useful to repeat them in tropical countries, with " sun-receivers " of suitable dimensions. We would measure the volume and the tension of steam produced in an hour by a given insolated surface, the pressure developed by the sun in a considerable mass of confined air, and the temperature which might be obtained by vast reflectors, formed of a framework of wood covered with plates of silver, etc. --------------- 4*------------- Tea Culture in this Country. A correspondent of the New York Times writing from Knox-ville, Tenn., gives some information, additional to that published on page 215, current volume, Scientific American, in relation to the culture of the tea plant in this country. Writing on this subject the correspondent says, in relation to Capt. Campbell's experiments, that his experience shows that tea can be successfully cultivated in East Tennessee, the climate of which is about the same as that in the tea-bearing regions of China and Japan. Frosts come late in the fall and leave early in the spring, and the winters are short and not severe. The writer says : The plant can easily be protected, and fhe experience of Mr. Campbell shows that it can be cultivated here without doubt. His farm is some ten miles southeast of this city, on the rich bottoms of the French Broad Eiver, and well situated for a fair test of culture. The plant is a deep evergreen shrub, and attains, at its full development, a hight of five feet. It is strong I and compact, and needs but little protection from the frost. It bears well ; it has a beautiful flower which develops about October. The next season produces a seed something resembling a hazel, which grows readily. Mr. Campbell has not at- tempted its culture to any extent. His idea was to prove fully its adaptedness to this climate rather than to embark in any enterprise in its cultivation. He has for some years raised all the tea he needed for his own family, and he feels quite well satisfied with its taste and the yield. It has been pronounced by several gentlemen fully equal to " Young Hyson," That he should have satisfied himself so long since of the adapted-ness of this plant to this climate, and that such conclusions liave not long since become known, and the enterprise been fairly tested on a larger scale, is a matter of surprise to me. It is a fact of great importance, as it seems to me, and it might be well for the Agricultural Bureau at Washington to encourage other and more extended experiments. If we can raise our own tea and our own beet-root sugar, we shall be relieved from a heavy expenditure which yearly inures to the benefit of the Chinese and Japanese. ------, ,-------- -.------------------ Galvanising Iron rawing off the Offensive Vapors. The application of zinc with tin as a coating for iron, says Van Nostrand's Engineering Magazine, has become a most important manufacture in and about Birmingham. The application of iron for every purpose of construction is practically only limited by the difficulty of preserving the surface from rust. No method has yet been adopted which is at once so cheap, so effectual, and so enduring as galvanizing, and the works in which that process is carried on have very rapidly increased. To galvanize iron it is immersed for a certain period in an acid to cleanse the surface, after which it is dipped into a bath containing zinc and tin melted. In this salts of ammonia are thrown, which operate on the metal as a solvent, and enable it to be more evenly distributed over the surface. From this bath is given off a dense, pungent, white-colored vapor, which is heavy, and, especially in damp weatli-er, spreads and becomes offensive. Complaints have been made of these vapors, and various plans have been adopted for the purpose of preventing them from passing into the atmosphere, but heretofore without success. The Wolverhamp-ton Corrugated Iron Company have adopted a plan which is found very effectual. The top of the bath is surrounded by a flue which forms a projecting lip, and from this, run one or more iron pipes communicating with a powerful fan. From the fan a large flue extends to an annealing furnace. The fan, by creating a vacuum in the pipes, causes a strong current of air to pass over the surface of the bath, which drives the vapor into the furnace, where it is entirely consumed. Experiments are in progress to condense the vapors so as to utilize them, instead of consuming them in fires. -----............-----, B "------------------ Casting Steel Under Pressure by use of Gunpowder. Casting steel under high pressure by means of gunpowder, is thus described by the inventor: It is well kaown that cast-steel run into molds is subject to blister, and is otherwise porous, which defect reduces considerably its toughness. In order to give this metal its requisite tenacity it is subsequently reheated and then rolled or hammered. As many articles, such as cannon, cannot be treated in this manner, I have devised to submit them to a high pressure while in a liquid state, inclosed in their same molds, maintained in iron flasks. For this purpose, immediately after running a cannon, I cover hermetically the head by a metallic cap, by means of bolts or other devices attached to the flask. This cap is fitted in its center with a vertical pipe, and provided with a cock at its lower extremity, while its upper extremity is closed by a washer pressed by a bolt in such a manner as to act as a safety valve. Before attaching the cap, at, supposing, one inch from the surface of the liquid metal, I introduce in the vertical pipe, and between the cock and the washer, a charge of about one quarter of an ounce of a powder, prepared in the. proportions of eighty parts of saltpeter and twenty parts of charcoal. On opening the cock this powder falls on the metal, ignites and engenders about one-third of a cubic foot of gas at 3,000 Fah. These gases exert on the liquid metal a pressure which is transmitted throughout the entire mass, thereby condensing the same and expelling the blisters. The effect thus produced is equivalent to the pressure of a head of liquid metal ninety feet high, admitting that the capacity between the cap and the surface of the metal contains thirty cubic inches. By making the flasks sufficiently strong, the charges of the powder may be varied, so as to produce by its ignition a uniform and general pressure, which is preferable to the partial, irregular, and momentary action of a hammer. Engineering Mag* azine. Louisiana Sugar and Sirup. An esteemed correspondent of Plaquemine, La., Mr. Evan Skelly, has sent us a barrel of sirup of fine quality, and some samples of sugar, made with his sulphur apparatus, for which he will please accept our thanks. He writes us that " the sirup was made direct from cane juice in common open iron kettles from six degree juice, plant and stubble cane mixed, with the use of three and a-half pounds of sulphur to the hogshead, limed 64 cubic inches to the grand, four grands to the hogshead of 1,000 pounds, made about the 25th November, 1868, (rather late in the season) on the Pecan plantation, in the Parish of Iberville, worked by Mr, David N. Barron, with one of my sulphur apparatus. I send also samples of sugar made with the apparatus on various places, that you may judge for yourself of the practical working thereof. It is well established in New Orleans, that a greater quantity of inferior sugar has been made in Louisiana this year than in any previous year in proportion to the crop, caused from the fact that most of the cane ground was plant, and generally planted in fresh land." The quality of the samples sent is such as substantiate the efficiency of the apparatus. In the manufacture of neither the sugar nor sirup, he adds, no chemicals were used except sul phuroug acid and lime. The sprouts of the potato contain an alkaloid termed by chemists solanine, which is very poisonous if taken into the system. This does not exist in the tubers, unless they are ex posed to the light and air, which sometimes occurs from the accidental removal of the earth in cultivation. Improvement in Thimbles and Ventilators for Funnel Flues. Unsightly tin plates or guards to cover funnel holes of unnecessary size in the chimney are not very pleasant adjuncts to the arrangements of the kitchen, dining, or sitting room. A perfect fit of the stove funnel to the thimble or sleeve makes'a neat appearance, whether the thimble is of tile clay, or of sheet or cast iron. The engraving represents a method of making a neat fit to any size of pipe. A is the thimble or sleeve to be seated in masonry of the chimney. It has snugs, B, which engage with recesses, C,on the flange that is one of a set intended to fit each size of pipe or funnel down to four inches. The register, D, is to take the place of the flange or collar in summer, when the stove and pipe are removed. It is secured in the same way as the collar, by means of a projecting circular flange fitting the interior of the sleeve, A, and the snugs and recesses as seen. This device can be attached or detached instantly, and it makes a neat, safe, and handy contrivance. ' Patented, Nov, 8,1868, by J. L. Little, who may be addressed for rights or for additional information at Atkinson, N. H.