Krupp's Works; MESSRS. EDITORS : Having been favored with a visit to the celebrated works of Fred; Krupp, Esq;, of this cit I think that a description of what was seen there may not be uninteresting to the readers of your journal* I have within the past few weeks visited the most extensive establishments of a similar natilre in England, and I find that most of them bear about the same relation to Mr. Krupp's works as a yacht does to the Great Eastern* That such a gigantic concern was built up, owned, and managed by one man is truly wonderful, and, in order that some idea may be formed of its extent, I give the following account, which was furnished me at Mr. Krupp's office : This establishment has been in existence forty-two years, and has steadily grown, year by year, until at present it covers a continuous surface of 450 acres, 200 of which are under roof. The men employed number about 14,000. In the year 1866, the works turned out 61,000 tuns of material, involving the use oi 412 smelting, reverberatory, and cementing furnaces; 195 steam engines, varying from 2 to 1,000-horse power; 49 steam hammers, from 1 cwt. to 50 tons; 110 smiths' forges; 318 lathes; 111 planers; 61 cutting and shaping machines; 84 boring machines; 75 grinding machines; and 26 sundry and special tools. There have been large additions to the above within the past three years. At the present time 180 steam boilers are used, evaporating 200,000 cubic feet of water into steam of 4 atmospheres pressure every twenty-fonr hours; and about 12,000 gas burners consume, in the same time, 500,000 cubic feet of gas—the gas being lighted night and day. There are about 20 miles of rails traversing the works in every direction, upon which run 7 locomotives and 150 wagons. The principal articles manuf actoed are Bessemer steel rails, crucible steer, breech-loading guns to 96,000 lbs. weight, cast-steel marine crank shafts, cast-steel locomotive crank axles with cast-steel disk wheels of 6 feet diameter. Here is the largest forging steam hammer existing; the " drop " alone weighing 100,000 lbs., and t'.ie casting for the hammer block 300,000 lbs. The foundation for this hammer is 60 feet deep, built up with timber and iron. I saw this hammer in operation forging a gun of the largest dimensions. One of the great secrets of the succes in making huge cast-steel forgings lies in having the weight of the hammer so proportioned to the size of the forging as to move the entire mass of metal at each successive blow of the hammer. While recently visiting the works of Messrs. John Brown & Co., Sheffield, England,—the principal productions of which are Bessemer steel and iron armor plates—I saw plates 9 inches in thickness. There is, however, a limit to the thickness of iron plates for vessels, for a ship may be sunk by the weight of her own artnor. But let us see what Mr. Krupp is doing. I was shown a 1,000-pound rifle breech-loading gun resting upon a cast-steel carriage. This gun was intended for coast defense service. It consisted of an inner tube upon which was shrunk cast-steel rings. The inner tube when finished weighed 20 tuns, and was forged from a massive ingot of 40 tuns; and the cast-steel rings, forming a threefold layer at the powder chamber and a twofold layer at the muzzle portion, weigh about 30 tuns—total weight 50 tuns. The diameter of bore was 14 inches, the total length 9 feet 2 inches, the number of rifled grooves 40, depth of rifling 0*15 in. the twist of rifling 980 and 1,014*4 in., the weight of solid shot 1,212 lbs., the weight of shell 1,080 lbs., and the charge of powder from 110 to 130 lbs. (The weight of shell was made up as follows: cast-steel shell 843 lbs., the leaden jacket 220 lbs., bursting chargel7 lbs.—total 1,080.) It required sixteen months to manufacture this gun, working day and night. This cannon reposes upon a steel carriage of the weight of 15 tuns and together they work upon a turn-table of 25 tuns. The total weight of cannon, carriage, and turn-table was 90 tuns. The gun carriage slides smoothly upon the turn-table, and the necessary mechanism for working the gun is such that one or two men can easily elevate, depress, and turn the gun, and can with the utmost certainty follow and cover any passing vessel. The cost of this gun mounted complete is $187,000 gold. There are in course of construction thousands of tuns of these guna of all sizes down to 4 pounders, all breech-loaders; and it is supposed that a single discharge of Mr. Krupp's 14-inch cannon will sink any iron-clad afloat. The cost of transporting one of these large guns would be enormous. No railroad car possessing "sufficient strength, Mr. Krupp manufactured his own car entirely of s'teel and iron, which rests upon twelve wheels, the total weight being 24 tuns. The coal bed which is beneath the works sxtpply the necessary fuel, and the continual undermining has resulted in a sinking of the eayth and conseque&t damage to the buildings, I was shown locomotive driving wheels, 6 feet in diameter with hub, spokes, rim, and crank all forged in one solid piece; the outside flange tire being shrunk on and fastened in the usual manner.. I saw also some railroad frogs of east-steel, and was told that they were cast in the same kind of clay, or earth, of which the steel crucibles are- made* They were as perfect as any cast-iron ca&tings, Mr. Krupp has orders from different governments for cannons su&cient to run his works for more than two years. 43 I passed over this vast establishment and viewed the immense masses of steel and the various appliances for handling, turning, and moving each piece, I wondered th&t so mtach could have been accomplished in a life-time., Bi&t thee- is every facility here for keeping p such, am establishment. Labor is cheap; mechanics about one $1 peir day and. ordinary labor from fifty to sixty cents. The surrounding country is all cut up into governments—some of which are of no larger population and of less territorial extent than New Jersey— and each must have its standing army. Little Belgium keeps in time of peace a standing army of 50,000 men. In passing over any part of this country one meets soldiers at every corner and finds them in almost every railroad car. All this implies a constant demand for the materiel of war. I find that the mechanics of Prussia are very much dissatisfied with the patent laws of the country, as they afford very little protection or encouragement to the inventor, and therefore do not serve to promote the arts or sciences. In ordinary pursuits and more especially in agriculture, work is performed in the most primitive manner. There is little to stimulate the inventive power of the mechanic, and it is only in a few large establishments like that of Mr. Krupp's that the genius of the country is to any extent developed. I think that the people of Prussia possess mechanical talent to a high degree, and that under more liberal patent laws she would in a short time stand side by side with any other nation. In warfare no doubt Prussia is the terror of Europe. The inhabitants numbering about 20,000,000, and every man having been educated as a soldier, she is thus enabled to raise an army sufficient to cope with any power. Mr. Krupp's works alone could supply her with weapons—in fact no government works in the world can at present equal nis in extent, or facilites for manufacture. When other governments are entering into contracts with MK Krupp for guns, they seem to lose sight of the fact that they are building up an immense establishment in another country, while they should by every means pratronize and encourage home industry. Equal patronage would soon raise an enterprising American establishment to the high standing of Mr. Krupp's. J. E. EMERSOK. Essen, Rhenish Prussia. Explosive Compounds. MESSRS. EDITORS:—I have read with much interest the articles which you have published on explosive compounds applicable for engineering purposes. The writer, however, does not give any information not hitherto known, and in gathering this he seems to have exercised but little discrimination. I will only refer to No. IY. of the series, respecting nitro-glycer-in. In this article he gives little except what can be found in chemical works, and nearly one-half of the article refers to the oft-repeated accidents that have occurred with nitro-gly-cerin. But allow me to call your attention to a few of the author's assertions. In the first place, he states that nitro glycerin is made from one volume of nitric acid, specific gravity, 1*43, and two volumes of sulphuric acid, specific gravity, 1*83, and that it will congeal at 40 Fah. Practically considered, the specific gravity of the nitric acid is not sufficient, and nothing short of 46 will give a commercial yield. The freezing of nitro-glycerin varies from 43 to 44 Fah. Nobel says he has had it a liquid at 32 Fah. In a frozen condition nitro-glycerin will not explode. An atom may be thawed by a blow, and the explosion of the atom will produce the detonation of the whole congealed mass. The scale for determining the explosive force of substances must be according to the expansion of the gases evolved. The writer gives 32,832 pounds as the average explosive force of gunpowder, because, on an estimate, a certain quantity of chalk was removed from the Dover Cliff's, of white sand, at Tunbridge, etc., with one pound of powder. He does not mention the quality of the powder, nor the conditions of application, whether or not the powder was placed so that the mere starting of the material would carry with it large quantities, as illustrated by chambering and barring. The expansion of gas developed on the explosion of an atom of nitro-glycerin may be thus considered. The chemical formula of nitro-glycerin is C6 H5 O3 (NOf)). Each 100 parts of exploded nitro-glycerin leave a residue of 20 per cent water; 58 per cent carbonic acid; 3*5 per cent oxygen; 18'5 per cent nitrogen; total 100. Specific gravity of nitro-glycerin 1*6, and one volume produces 554 volumes of steam; 4G9 volumes of carbonic acid; 39 volumes of oxygen; 236 volumes of nitrogen; total, 1,298, or nearly 1,300 volumes. Artillery engineers have determined that only 32-100 of any charge of gunpowder can be exploded or converted into gas, but say 50 per cent, one volume giving 260 volumes, cold gas, deduction being made of the expansion produced by heat. Practically, however, the combustion is never so complete, and 200 volumes cold gas are, therefore, in all probability, above the real average result. It is difficult to determine the degree of heat produced by an exploding substance. According to th'eory, however, nitro-glycerin, on aecount of its complete combustion, ought to develop a much greater heat than gunpowder, and this is often shown by the rock located near the charge in a blast. The rock is disintegrated, and the hardest stone is easily broken with the hand. The heat evolved may be safely considered to be three times greater than that thrown off on the explosion of gunpowder; but I will base my estimates upon twice the degree of heat. The above facts being realized, we may conclude that, if one volume of gunpowder gives 200 volumes cold gas (practically, however, only 173 volumes), expanded by heat four times— equaling 800 of explosive force, and nitro-glycerin cold gas as above given, at 1,300 volumes, expanded by heat eight times—produces 10400 volumes; so that nitro-glyceri, compared with gunpowder, possesses about thirteen times its power when volumes are considered, and eight times, considering weight,, the specific gravity of gunpowder, being 1*0. In hard or wet rock, nitro-glycerin remains without an equal, and the particulars regarding the resiilts of practical blasting-must be considered in a future communication. What we fail to learn in the series above referred to, are practical experiments in the disruption of matter by these different explosives under like conditions. It is not for me to suggest how these experiments may be made, and perhaps the only way that their powers can be determined is by considering their chemical forces. The writer seems to suppose that nitro-glycerin has passed from any use in practical blasting. That may be so in the British Isles, but he ought to remember that the people of that country are very slow, and that men of enterprise have to struggle long, and with much patience, to get them to adopt new improvements, even after the commercial value of an invention is beyond doubt. TAL. P. SHAFFNER. Galvanized Iron Water Pipes, MESSRS. EDITORS :—An article in No. 18, Vol. XX. May 1st, asks if galvanized iron pipe is fit to convey water for culinary purposes. I will give you my experience. About six years ago I put down some 60 feet of lf-inch galvanized iron pipe, to convey water to my kitchen. Galvanic action took place immediately, and the water become so offensive from hydrogen gas liberated, that we could hardly stay in the room. My pump worked so well that I thought that I had better try to remedy the detect, so I proposed making a thin wash of hydraulic cement to coat the inside; but before trying it a heavy rain muddied the water in the well, and when it had settled and become fit to use, it had lost all the offensive taste and smell and has been good ever since. I would recommend a very thin wash of hydraulic cement and not wait for the rain. P. M. Paterson, N. J. [The reaction described by our correspondent always occurs, to a greater or less degree, when water is first admitted to a galvanized iron pipe. The zinc is oxidized at the expense of the water which leaves hydrogen free. No harm, however, is to -be apprehended from the effects of this gas, except a trifling temporary inconvenience. It is the subsequent dissolving of the oxide of zinc that renders the water hurtful. This we have shown does not take place except when impregnated with substances specified in the article referred to by our correspondent. If the water is free from these substances the use of cement is unnecessary, and if they are present such pipes should not be used.—EDS. Extinguishing of kerosene Lamps. MESSRS. EDITORS:—A kerosene lamp will be found extinguished in less than one minute from the time of complete disappearance of wick below the edge of tube through which it passes; care being taken not to turn it out of reach of that part which controls the action upward and downward. It I s better to allow it remain turned down till relighting—absorption does not occur, gumming is avoided, and destruction of wick is retarded very materially, as the wick is constantly chargedwith oil. But if turned up after being extinguished, the wick becomes dry, and quite an amount thereof is consumed before concomraittant actions of combustion come into play. Blowing into the chimney, or under it, is unnecessary, and quite unphilosophical, as a deleterious gas is cv; Ived until wick and tube cool. ENTERPRISE. Cincinnati, Ohio.