V1. An Account of a new Method of increasing the charging Capacity of coated Electrical Jars, discovered by JOHN WINGFIELD, Esq., of Shrewsbury*, and communicated to Mr. JOHN CUTHBERTSON, Philosophical Instrument Maker, of Poland Street, Soho; with Experiments proving the above, by Mr. JOHN CUTHBERTSON. IN my treatise, entitled Practical Electricity and Galva- Breathing into nism, p. 103, I have said, that breathing into coated jars jars increases their capacity increased their charging capacity to such an astonishing for a charge. degree, that their discharge would fuse four times the length of wire they could do in ordinary circumstances, which I proved by experiment, p. 178, 194. batteries, Since that publication large electrical batteries are be- This inconvecome more general, and the number of jars increased, so nient in large that batteries containing thirty, sixty, and even a hundred and more jars are frequently met with. When so numerous, breathing into each jar is very disagreeable; and not only that, but, when the atmosphere is very dry, and when it is most wanted, it is even ineffectual; because the jars, which were first breathed into, lose that property which was produced in them by breathing, before the last can have obtained it; so that a variety of other means have been tried, and moistening such as wetting their insides with water, and putting wet with water insponges into them, and also greasing and oiling the uncoated part in the inside, all of which gave unsatisfactory results; till John Wingfield, Esq., communicated to me, that pasting Paper pasted, paper on the inside and outside of coated jars prevented inside and out. them from exploding to the outside coating, and that he believed their charging capacity was increased thereby. effectual. I embraced the first opportunity to try the effect of this Trials of this. discovery with single jars. Exp. 1. I took a very thick jar (which had been used • A gentleman who has lately very much distinguished himself, not on'y in the electrical science, but in all other branches of experimental philosophy. VOL. XXVII-Nov. 1810. P te Exp. 1. Exp. 2. Exp. 3. Exp. 4. Exp. 5. Exp. 6... Exp. 7. to show the phenomena of voluntary explosions without breaking) twelve inches high, and the coating nine inches, containing in the whole 171 square inches. It was applied to the conductor of a plate electrical machine, and six turns of the plate caused a voluntary explosion. The state of the atmosphere not being very dry, it required eight and twelve turns, to produce a second and third explosion. A fourth could not be produced; but, when cleaned and dried, as before, six turns caused a voluntary discharge. Exp. 2. A slip of paper one inch broad was taken of sufficient length to fit the outside of the jar, when the two ends were pasted together. This was slipped on the outside to about one inch from the coating, the uncoated part being rubbed clean and dry, and applied to the machine, eleven turns of the plate produced a voluntary discharge to the ontside coating. Exp. 3. The paper ring was then slipped down to touch the coating, and then applied to the conductor, no voluntary discharge could be produced, and when discharged in the common way, its power did not seem to be increased. Exp. 4. The common discharging electrometer (which is always fixed to the basement of my machine) was used, to try to what distance the discharge could be made to pass from the knob of the conductor to the ball of the elec trometer, which was found to be one inch and §. Exp. 5. A piece of iron wire part of an inch in diameter, and one inch in length, was hung to the electrometer, through which a second discharge was made to pass, and the colour of the wire was changed to a blue. Exp. 6. The paper ring was then taken off, and I breathed into the jar twice; the discharge was then produced at the distance of two inches, and the wire was fused into balls. Exp. 7. The jar was then rubbed clean and dry, and a piece of the same sort of wire, of the same length, was hung to the electrometer in the same manner as before, and it appeared, that the greatest charge it could take had not the least effect upon the wire. Thus it appears, that a paper ring so applied does not increase the charging capacity of jars in the same degree as breathing. Exp. 8. The jar was highly charged, and examined in Exp. 8. the dark. The paper ring appeared luminous all round the uppermost edge. Exp. 9. The ring was then taken off, and pasted on in Exp 9. the inside close to the coating. Twenty-three turns caused a voluntary explosion, through the ring, to the outside coating. Exp. 10. A second ring, of an inch broad, was then Exp. 10. pasted on close to the other. The same number of turns produced a voluntary explosion, and the paper was torn by the discharge; after which it was repaired, and left to dry. Exp. 11. When dry, no voluntary explosion. could be Exp. 11. obtained. Exp. 12. Its greatest power was then tried, and it was Exp.-12. found exactly the same as in Exp. 6, when it was breathed into; it discharged at 2 inches distance, and the same length of wire was fused into balls. Exp. 13. A second jar was taken of a larger size, being Exp. 13. 13 inches high, and its coating 7 inches, it contained about 190 square inches. After being rubbed clean and dry it was applied to the conductor of the machine, 12 turns of the plate produced a voluntary explosion to the outside coating. Exp. 14. A paper ring was put round the uncoated part Exp. 14. on the outside, at about 1 inch distant from the coating. Eleven turns of the plate produced a voluntary explosion to the outside coating. The paper ring was then pushed down to the coating, after which no voluntary explosion to the coating could be obtained, but it discharged to the electrometer ball standing at the distance of 2 inches and from the knob of the conductor. Exp. 13. Exp. 15. The same sort of wire as used in Exp. 6, two inches long, was hung to the electrometer, and the discharge made it blue, with several bendings: a proof that it had been neatly redhot. Exp. 16. A ring of common writing paper, one inch Exp. 16. broad, was pasted on the inside close to the coating; aud when dry no voluntary explosion to the coating could be ebtained, but it discharged itself to the electrometer ball standing P2 Exp. 17. Exp. 18. Exp: 19. Exp. 20. Exp. 21. Exp. 22. Exp. 29. Exp. 24. standing at the distance of 24, and the wire was fused into balls. Exp. 17. The paper rings were now taken off, and the uncoated part made clean and dry. Nineteen turns produced a discharge to the electrometer ball at the same distance, and the same length of wire was slightly blued. Exp. 18. The jar was then breathed into, and a discharge was produced at the same distance, but the wire was not fused. Exp. 19. The same jar was breathed into a second time; a discharge was caused at the same distance, and the wire was fused into balls exactly the same as when the paper rings were on. Exp. 20. A third jar was taken, 7 inches high and 4 inches diameter, having about 64 square inches coating. When rubbed clean and dry, and applied to the machine, two turns of the plate caused a voluntary discharge to the outside coating. Exp. 21. A paper ring was pasted on both sides, close to the coating, and one inch from the top. When applied to the machine, no voluntary explosion could be obtained, but the electric fluid was seen to run over the brim of the glass to the coating as quickly as the machine could give it. The exploding distance to the electrometer was seven eighths of an inch. Exp. 22. The paper tings were taken off, and others pasted on, to within one inch and a half from the top. No voluntary explosion to the coating could be obtained; but it exploded to the electrometer standing at one inch distance, and did not produce any effect on one inch of wire, which was hung to the electrometer. Exp. 23. Then paper rings of different breadths were tried, and it was found, that, when they were only half an inch higher than the coating, the jar received the greatest power, and its exploding distance to the electrometer was one inch and three eighths, which fused and dispersed in balls one inch of wire, of the same diameter as that used in Exp. 6, with the first jar. Exp. 24. The paper ring was scraped from off both sides, and the jar was carefully breathed into. Then six turns of the the plate caused its longest discharge to the electrometer, which was at the distance of one inch and three eighths, and fused one inch of wire, but with less violence than in the last experiment. Exp. 25. The outside paper ring was scraped off, and Exp. 25. the jar still preserved the same charging capacity, as when both were on. The above experiments are sufficient to prove, that paper General con rings pasted on to electrical jars not only prevent them from clusions. exploding to the outside coating before they have received their highest charge, but that they likewise increase their charging capacity; and that one ring pasted on in the inside only is sufficient, if it is one inch broad; one half of the breadth must be pasted upon the coating, and the other upon the uncoated part. Farther experiments and observations, setting forth the advantages that electricians may obtain from the above discovery, with an account of some experiments done with a view to prevent the jars from being perforated by high charges, without increasing their thickness, wherein I am in hopes I shall succeed, will be the subject of a future paper. VII. On the Combinations of Oxigen. By MARSHALL HALL, Esq. SIR, To Mr. NICHOLSON, THE utility and excellence of axioms in science are too Axioms of science. well known to those, who are earnestly engaged in its pro- great use in secution, to require to be expatiated on. The few observations on the combinations of oxigen, which I take the liberty of transmitting to you, do not perhaps deserve the dignified name of axioms; but where coincidences are so general and striking, we are led, perhaps too soon indeed, to believe them universal. If however I shall point out what generally takes |