The Optical Magic Lantern Journal (May 1891)

110 = The Optical Mazic Lantern Journal and Photographio Enlarger. two-fold. in a bag or a cylinder, there must be maintained two quite distinct currents of gas—one which carries a supply of oxygen which takes along with it a much larger measure of ether vapour than of oxygen (it should carry about eight parts of ether vapour to one of oxygen), and a second supply of oxygen which is entirely free from any trace of ether vapour. In order to make my meaning clear, I givean illustration of the apparatus | have used; but in any modifications the same points will require attention. A represents a yas-bag filled with oxygen gas ; this passes by the tube B into the vaporiser at D ; the gas Passes through one tube of the vaporiser into the second tube, passing out at H. Into the vaporiser is placed one and a-half pints of . ether. There must be sufficient fluid to fully saturate of which lighted with a crack. the stuffing of the vaporiser, and to leave fluid enough below the gas-way to supply the place of what | is drawn off by the oxygen. There is also a branch union for the supply of the pure oxygen, as per illustration. First, let us pay attention to the oxygen which has passed through the vaporiser, and learn by sight when the vapour is quite safe to handle. vapour through the jet before attempting to light it ; turn off the gas, and allow the vapour to dissipate ; then turn on the light, noting carefully the character of the flame (this best done by withdrawing the lime). If the sample of ether is good for the purpose the flame will be luminous, and when the flame is applied to the lime it will not heat it to white heat. Sucha flame is quite safe ; it will burn in all respects like : ordinary gas, and with a burner of ordinary aperture, and so far as this supply is concerned, if a flame is obtained which gives light, and will not heat the lime, ali is safe. Now turn on a little oxygen, and note the character of the flame—it is reduced in size, is not luminous, and it heats the lime to white heat. It is quite possible to get the non-luminous heating flame from the one current of oxygen and vapour, and then you are very close to a dangerous condition when the current of gas is explosive, and everything is easy for the light to pass backwards. A light which is safe one minute will not alter its character directly, and become explosive. With anything like suitable tools it will only change from safe to dangerous in half-anhour or so, and not _ then if you are master of the position ; but. the possible change must be understood. This possible | change may come about from there not being a sufficient || supply of fluid in the ; vaporiser, a reduction of temperature, or the sample of fluid be: ing unsuitable. These points have often been } dwelt upon, and it is not here that there | pass back to the bag or contamin : back by regulating the supply at the Pass a little of the | From one common stock of oxygen, either | possible danger of getting an explosive mixture in the other supply, which I now come to consider. In this form of the limelight we get over one difficulty—the pressure will always be the same on both the currents, the inflammable and non-inflammable. If readers will notice the illustration, they will see that at the point B the two streams are very close together, and if care is not taken, the vapour of ether may ate the oxygen supply in the tubes. In my early practice I found such to be the case, and until I found the simple remedy for this, the light was unmanageable. I made several bags of gas, which were quite explosive—the least quantity In the directions I published, I put it asa first precaution. The vapour ofether is prevented from passing inlet at D, and opening fully the tap H, and keeping the tap at the jet open. hot I ‘have said that the icondition of the safety as regards the inflammable supply of gas will not alter quickly from a_ safe to a dangerous condition ; but it must be evident that where it depends upon the introduction of only a small quantity of vapour into the limited area of the supply tubes, a change may much sooner take place. But here there is a simple indication to guide the operator. If the oxygen supply is pure, and the other supply fully charged with ether, the smallest reduction of the oxygen supply will cause the light to go down; and, on the contrary, if a wrong condition is coming on, a reduction of oxygen will not affect the light as much.; ¢-— The form of the vaporiser has a good deal to do with its continued action. I have one which I cannot use an hour or a half without i being obliged to turn it over duri ing the exhibition, or it does not i | continue to saturate the oxygen with vapour. This is because it is made to stand upright about gin. I find quite a shallow vessel is decidedly the best. Pore Uxveen Tuse (NFLAuMAaLE OXYGEN TUBE. has been most often failure; but I think the attention has not been directed to the