(12542) H. S. D. asks: Have you any publications regarding the making or lee by the vacuum process? I have placpd a slllall amount of water under a bell jar with some sulphuric acid and have exhaust<d the air. The wa ter cools but fails to freeze. According to theory, should water freeze under the ahove conditions? Can you suggest any Ilwthod for freezing water undEl' vaeuum? .\. 'Jhe rxperiment of freezing water under a bell jar or a common air pump is a vel'y ditC1l1t OBP. ''he vacuum is usually too low. The metal of the pump conducts heat into the wa Ler nearly as rapidly as the evaporation takes it out of the water. With a quick-acting high· grade pump, and by protecting the glass in which the water is contained from the metal of the pump, the freezing of the water will occur, but not rapidly. A very small and broad bell jar must be used. '1he sulphuric acid must be in a broad dish. The wa t",. is usually in a flat watch glass over the acid, supported by a wire frame which rests upon the glass dish in which the acid is put. The older bOQks of physics usually have pictures of the arrangements. You will find it in Deschanel, Yol. II, as well as the picture of Carre's apparatns for freezing water in bottles by the same method, which was once largely used, but has now gone out of use. (12543) F. K. writes: Occasionally I see mention made in your valuable journal by writers claiming to havp sePl ball lightning drop from the clouds, the accuracy of whieh is questioned by some and as being an illusion. I distinctly r('nwmber one afternoon about 4 o'clock having seen such a ball drop from the clouds ; was from. a thunder cloud in the northwest sky. I was facing the cloud at the time. To me it appeared to be about six inches in diameter, and as it descended sparkled with sbort electric bristles until it reached terra firma. I ,as Heturning from a feld at the time, and take distance between me and where it reached the earth to have been about half a mile. 'his was at Centerhall, Pa. I at once concluded when reaching the village to inquire whether the phenomenon had been 0 bserved there, and to my astonishmen t learned that “lightning had struck the house of Alex. Shannon,” followed the chimney down into the kitch(, where a little daughter was standing close to the range, and was instantly killed. There was no other flash of lightning a t the time, Iwnce there can be no doubt that the ball lightning killed the little girL The ball was about two and a half seconds in its descent. A. There was a time when the existence of a slowly moving globe or shining ball of eleetricity, which afterwards might explode with great fore", producing all the effects uf a lightning stroke, was denied and even ridiculed [y scientific men. We think all now admit the reality of these occurrences. (12544) W. F. M. asks: 1. Is iron or st<-el while very hot, or in a molten state, absolutely unaffected by magnetic lines of force? A. Iron or steel above red heat cannot be magnetized. 2. Will a thin shect of iron held in front of the poles of a powerful magnet cut off all the “pull” of the magnet? A. A thin sheet of iron will not cut off all linps of magnetic force. A plate of suffiei('nt thickness to furnish a path for the lines of force hclow saturation must be pl·ovid", For wrought iron about 100.000 lines can be carripd p('r square inch of cross section. gvrn then there will be leakage into the air. (12545) W. G. M. asks: I have a pipe that leads from my well 14 feet higher than my sink. I fill the pipe with water. and the water will flow from three to five days, then stop. I have put a pump on and suckel the water down and have the same trouble. I have to lift the water about 4 feet from surface to where the pipe turns to go down. I would like to know the cause of its stopping. or how I can remedy it. A. 'he intermittent action you describe is inevitable with the simple siphon. Ail' carried into the pipe with the water escapes. as th0 pressure is reduced during the passage of the water up the pipe. and collects in th'l oe'1d. 'Yhpn sIlfci{'nt ail' has accumulated, the water column lJrpaks and the flow stops. When this occurs the air must be removed by pumping it out or by refilling the pipe with water. These interruptions may be delayed by providing an air chamber at the high point of the siphon. so that the air may called for a longer time before it interferes with th” fow in tbe pipe. With a cock below tbe ail chamber, and a ping or cock at the top, the whore air chambel' may be filled with wHtpr whenev0l' til collected ail breaks the Bjphon's flow.