The Optical Magic Lantern Journal (August 1893)

114 The Optical Magic Lantern Journal and Photographic Enlarger. Briefly it is this :—The cylinder is immersed in an iron envelope which is filled with water, and by a clever arrangement a tight joint is made | around the neck of the bottle. The requisite | pressure is applied by means of an hydraulic pump, and the water displaced by the stretching | of the cylinder is raised up a glass tube which communicates with the iron envelope in which | the cylinder is placed. The pressure of 4,000 lbs. to which these bottles are tested is suflicent to raise the column of water in the tube nearly two feet. On the pressure being released, it is a sine qua non that the water in the gauge shall fall back to its original height : thus indicating that not only has the cylinder withstood the © necessary pressure, but also that it has not been ' over-Strained or suffered any permanent stretch. © If the bottle fails in this respect it is promptly rejected, ‘Therefore beginners may have perfect faith Inthe trustworthiness of all cylinders subjected to this test. If, in some unlooked for way, a cylinder did afterwards become unable to withstand the usual pressure, this weakness would become apparent whilst it was being filled, and for this reason: A considerable amount of | heat is developed during the process of filling, | so that in order that the cylinder shall contain the proper amount of gas when cool, a rather greater amount of gas, so to speak, has to ; be pumped in. would register nearly 15 feet when first filled. The subsequent contraction of the gas by the radiation of this heat lowers the pressure and makes an explosion in the user’s hands altogether unlikely. With regard to the practical use of these cylinders, the following hints may be of benefit to inexperienced operators. On receiving the cylinder from the dealers, first examine it for lcakage, for sometimes the rough usage the valve gets on the road will start a slight escape. Fill the opening of the valve with water—a bubble or two will at once denote leakage if present. Next fill the gland nut in the same way ; if it leakes tighten it up slightly with a spanner. The use of the gland nut isto prevent escape ; round the spindle on which the key fits. If all . is right, open the valve sharply for an instant | to blow out any dust, etc., which may have lodged about the entrance. In closing the valve use just sufficent strength to shut the gas off, aud no more. Always wipe both the cone and seating clean before coupling fittings to a cylinder. In order to make a perfect joint it is often necessary to tap up the union gently with the key or spanner. The smallest leaks can always be detected cither by putting one’s t Thus a 12-foot oxygen cylinder | i connection. ; chipped or injured. ear close to the joint or else by the use of water ; never use a light to locate a lcak, it is not necessary and sometimes not safe. Before connecting a gauge or regulator it is a ' good plan to first open the valve until the gas can just be heard escaping and then make the In shutting off the gas turn from left to right and remember that a valve is not a ‘‘try your strength’? machine. After closing the valve wet your finger on your tongue and draw ifover tne nipple ; if the film thus left rises in a bubble the valve is not shut gas-tight. For single lanterns automatic regulators are not absolutely necessary, a longish lever key and an easy-going valve will give full and sufficient control over the oxygen supply. Non-automatic Regulators, such as Noakes’, are very useful for single lanterns. Great care must be taken to prevent the threads of screw fittings from being It is useless to attempt to to make a joiut perfect by means of soap, white lead or anything of that sort, and, above all, oil or greasc in any form must never be applied to any part of the valve or fittings. -——!0: —— A Dissolver of 1848. By Jex Barpweuu (Detroit). ; As a discussion has recently been going on in i these columns respecting the date at which dis| solving views were introduced, I submita sketch . of a dissolving fan which I purchased with other apparatus cither in 1848 or 1&49 froma . ' Mr. Collins, who was at that time connected with the Royal Polytechnic, London. The = , lanterns were lighted with oil (circular wicks), i and were placed side by side, whilst immediatcly in front was set the dissolver. AA being the lenses of the lanterns, BB the covers for same. The correct height could be adjusted hy the screw C. The cover BB were capable of a slight side adjustment. The dissolving was effected by moving the lever up or down, so that when one lens was open, the other remained covered. This particular lantern I speak of was used by me publicly in Michigan in 1850-51.