Ink for Steel Pens.*

Professor Runge has long sought to obtain an ink which would not yield sediment, which should adhere to paper, resist the application of acids, and have no action on steel pens. He has at length obtained a liquid of this kind, containing only Campeachy wood, chromate of potassa, and water. As it contains neither vinegar, gum, sulphates of iron and copper, nor galls, its cost is very moderate. The proportions are 500 litres decoction of Campeachy wood to 500 grammes chromate of potassa. The Campeachy wood is boiled in a sufficient quantity of water to form 80 litres (4 litres = 1 English gallon) of decoction from 10 kilogrammes of wood (about 20 lbs). After the liquid is cool, the chromate is added and the whole well stirred. The ink is then ready and may be used at once. Any addition of gum would be injurious. It may appear strange that so little chrome should convert so large a quantity of decoction into ink. But the proportion must not be exceeded, as a larger amount would destroy the coloring matter. If, on the other hand, the proportions here given are observed, a blackish-blue is formed from the yellow pigment of the wood. This is not a suspended precipitate, like the gallate of iron in common ink, but a true solution, from which no sediment can be deposited. A paper written with this ink may be immersed in water for twenty-four hours without injury. Dilute acids do not destroy it or change its tint. The pens used with this ink should be perfectly free from grease, and may for this purpose be cleaned by immersing them in ley of wood ashes.

Description of a Rotary Steam Valve.†

Mr. Locking gave a description of a rotary valve engine, invented by Mr. Cook, a working mechanic, of Hull. In this engine a metal disk, with three apertures, slowly rotating on a flat surface, with corresponding openings connected with the boiler and cylinders, supplies the place of the ordinary slide valves. Rotary motion is given to the valve by means of bevel gear fixed to the crank shaft and valve spindle, the pinion on the crank shaft being to the bevel wheel on the spindle in the proportion of three to one, so the valve makes only one revolution in the time the crank takes to revolve thrice. The valve has three perforated apertures or steam ways, beneath which, in the face of the seat upon which the valve works, are four steam ways, two each for the right and left hand cylinders. The valve is so constructed that the steam ways through it pass over those in the seat, giving to the steam free access from the chest to the cylinders alternately, above and below the piston. Like the slide valve, it is chambered, and the steam escapes to the exhaust pipe, the air, or the condenser, as in ordinary engines. Reversing is effected by a lever and sliding box, each end having a slot, one of which is straight, the other diagonal, the length of each being equal from point to point on the box longitudinally; the transverse distance of the diagonal being one-sixth the circumference of the box. Through these are pins made fast to the valve spindle, that keep the box in its position, only allowing it to move up and down when the lever is lifted or pressed; the spindle being in two parts, and forming a junction immediately between these pins, in the centre of

From the London Artizan, October, 1853.

From the London Civil Engineer and Architect's Journal, October, 1853.

the box. By moving the lever up or down, the spindle with the diagonal alters its relative position to the other with the straight slot; thus the valve is carried round one-sixth of its revolution, thereby changing the position of the steam ways, and reversing the engine. Both cylinders will receive and cut off the steam at the same point, and thus prevent one valve rod wearing more than the other, on one eccentric being before the other. Another advantage of the valve is stated to be greater facility in working the steam expansively, and cutting it off at any point of the stroke. The cost of the engines will, it was said, be much less than those now in use. Consisting, too, as it does, of little more than cylinders and cranks, it will be much less liable to get out of order. Another advantage is, the great ease with which the engine may be reversed when the steam is full on; the engineer, by the use of a single lever, can regulate to a nicety the quantity required, and ease, stop, or reverse at pleasure.

The annexed engravings and references explain the different parts of the valve and its action:-v, valve; c, valve rod; A, B, cylinders; D, D, piston rods; E, E, connecting rods; F, reversing wheel; G, bevel wheel

and pinion for working valve. 1, aperture for the admission of steam to valve; 2, the valve upon its face in steam chest; 3, 4, steam ways above and below piston in cylinder a; 5, 6, steam ways above and below piston in cylinder B; 7, exhausting pipe into condenser, or (if high pressure) into the air; a, b, c, (fig. 4,) steam ways or apertures through valve to admit the steam to cylinders. The same are shown by the dotted lines on fig. 2, in which one of the apertures in valve coincides with No. 5 steam way to cylinder B; the direction of the rotation of valve is indicated by the arrow. d, d, d, d, chambers for exhausting steam through valve to exhausting pipe No. 7. e, e, e, shows the lap upon the valve.

Fig. 3.-Section of Valve.

Fig. 4. Working Face of Valve.

Mr. Oldham said, he considered it a decided improvement on any valve he had had an opportunity of examining.

Mr. Fairbairn said, it contained many important elements of improvement, but he did not see how it would save time, or how it would be more economical than the ordinary engine. Altogether, however, it appeared to him to be a very happy effort in the right direction.

At the conclusion of the business, the members of the Section paid a visit to Messrs. Locking and Cook's works, to inspect a steam engine constructed on this principle in action.

On Steam Boiler Explosions.'

At the British Association, Mr. Fairbairn, C. E., read a paper detailing some very interesting results of researches made for the purpose of determining the strength of locomotive boilers, and the causes which led to explosions. These researches were entered into in consequence of some difference of opinion having arisen between Mr. Fairbairn and Mr. Wynn, connected with the railway department of the Board of Trade, as to the cause of the recent explosion of a locomotive engine at Longsight. Mr. Fairbairn, upon examining the boiler a few hours after the explosion, found one side of the fire box completely severed from the body of the boiler, the interior copper box forced inwards upon the frame, and, with the exception of the cylindrical shell which covered the tubes, the whole of the engine was a complete wreck. The engine was made in 1840 by Messrs. Sharp, Roberts & Co., had been worked at a pressure of 60 lbs., and had run altogether a distance of 104,723 miles. The cylinders being only 13 inches diameter, the engine had, for some time past, been considered too light for passenger trains, and had been used principally as a pilot engine. The fire box, originally7ths of an inch, was, at the time of the explosion, a little over 3ths, and, from its excellent condition, might have been supposed but to have recently been put into use; it was perfectly free from flaw, and might, but for the accident, have traveled 100,000 more miles. The engine had been in the repairing shop about three months previous to the accident, and the whole of the stays had From the London Civil Engineer and Architect's Journal, October, 1853.

been tested by the hammer, in the usual mode. The only point which could admit of doubt as to the safety of the boiler, was with respect to the hold which the stays might have in the fire box. Experiments, however, had proved that the force required to pull some of the stays out of a copper plate similar to the fire box, into which they had been screwed, could not have been less than a pressure of about 300 lbs. per square inch. It required a dead weight of 8204 lbs. to pull out the "stay," and, as each "stay" had to support a surface of 27 square inches, it would require a pressure of 303.85 lbs. per square inch to strip the boiler. Supposing the stays to be riveted and sound in other respects, it would require a strain of not less than from 450 lbs. to 500 lbs. upon the square inch, in order to strip the screws or tear the stays asunder. In the case of locomotives of more recent construction, where the stays were thicker, and formed into squares of from 4 to 4 inches, the resisting force would be increased from 700 to 800 lbs. on the square inch, or at least seven times the working pressure. Considerable stress has been laid upon the weakness of the stay which united the flat surface of the boiler to the sides of the fire box. The experiments made, however, clearly indicated that the fire box stays were not the weakest parts of a locomotive boiler, and that we had more to fear from the top of the furnace, which, under severe pressure, was almost invariably the first to give way. Great care, therefore, ought to be observed in the construction of this part. The cross beams should not only be strong, but the bolts by which the crown of the fire box was suspended should also be of equal strength. It was in order to determine, if possible, by actual experiment, the laws on which these powers were founded that he had undertaken this series of experiments. The directors of the London and North Western Railway Company had placed in Mr. Fairbairn's hands an engine of the same age, constructed by the same makers, and in every respect a fac-simile of that which had exploded. The engine was subjected to hydraulic pressure in the following manner. The boiler was furnished with a valve of one inch area, and the lever gave as the weight upon the valve 35 lbs., the scale being suspended indicated 50 lbs. The abstract of the results was the following:

With this last pressure one of the bolts of the cross bar over the fire box broke, which caused the experiment to be discontinued, as the leakage was greater than the force pump could supply.

It had been stated that the steam could not have been raised from 60

lbs. pressure per square inch for that stated by Mr. Fairbairn, in so small a space of time as 25 minutes. Experiments, however, tested by Bourdon's steam gauge, had shown that the pressure could be raised from 30 lbs. to 80 lbs. per square inch in 11 minutes. It was considered necessary, however, to carry these experiments to a still higher pressure than 80 lbs., and to ascertain not only the exact time, but the ratio of increase, and the current of temperature of the steam in the boiler. In order to carry out these experiments, two delicately constructed thermometers were prepared by Mr. Dalgette, and Bourdon's pressure gauge having been adjusted with a column of mercury, the following results were obtained, on the 7th May, on a locomotive engine, with the safety valve screwed down and the fires lighted under the boiler:

This experiment was lost, the thermometer not indicating a higher pressure. The results deducible from these experiments were at the rate of increase in the accumulating force of the steam, and the equivalents in temperature corresponding thereto. In the first experiment the pressure was raised from 30 to 80 lbs. in 11 minutes; but in the latter, from 11.75 to 111.75, or not less than 100 lbs. in 22 minutes. Other experiments were made for the purpose of testing the strength of stays in the fire box. Two thin boxes, each 22 inches square and 3 inches deep, were constructed, one of them corresponding in every respect to the sides of a fire box of the exploded boiler, the other of the same thickness of plates, but the stays arranged in squares 5 inches asunder. Tested by hydraulic pressure, it was found, on the 19th experiment, that, with a pressure of 785 lbs. per square inch, the side swelled '08 inch, and with the 20th, with a pressure of 815 lbs., the box burst, by drawing the head of one of the stays through the copper, which, from its ductility, offered less resistance to the pressure on that part where the stay was inserted. These experiments were conclusive as to the superior strength of the flat surfaces of a locomotive fire box, as compared with the top or cylindrical part of the boiler; but other experiments, in which the stays were closer together, showed that a resisting force was obtained much greater than any which it could possibly have to sustain. For instance, in the case of boilers where the stays were arranged in areas of 16, instead of 25 square inches, he had found, on the 47th experiment, that a pressure of not less than 1625 lbs. on the square inch, producing a swelling in the sides of 0.34 inch, was required, in order to draw the stay through the plate, after sustaining the enormous strain for one minute and a half.