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Show By an Automobile Expert. If there is anything not clear to you, ask tho automobile editor about it. An answer will be published on the completion of the articles pertaining to J each section under discussion. I LESSON NO. 20. Mixtures. We now come to the study of the carbureter. To clearly understand he action of tins most important device, I will first have to explain some of tho simple chemical and physical phys-ical laws upon which its . action is based. j Scientists call the smallest particle of which all matter wood, iron, water, j air is composed the molecule. Thus, j a drop of water is composed of millions mil-lions of molecules, as is "the gorm which is so small as not to be visible under the strongest microscope. The molecules of which this germ is made will haVe different chemical compositions; composi-tions; thus, those of the heart will be different from those of skin, flesh or bones. The chemist works with these molecules. mole-cules. He divides them into what he calls atoms, and re.ioins these atoms ! into other conbinations Thus each molecule of water is composed of two atoms of hydrogen and one of oxygen, and each molecule of gasoline is composed com-posed of eight atoms of- carbon and eighteen of. hydrogen or thereabouts, depending upon its grade. A chemist can divide the gasoline molecules into their elements or atoms; that is, carbon car-bon and hydrogen, an3 then make the carbon combine with some atoms of oxygen, and the hydrogen atoms with i other atoms of oxygen, and so change the gasoline into what is known as I carbon dioxide gas and water. ' These atoms or elements of which ! molecules .are made are much like hu-; man beings, in that they, like to be combined or in company with certain elements more than with others. Thus most elements like to combine with 1 oxygen, while few will readily combine com-bine with nitrogen Carbon and hv-drogen, hv-drogen, of which gasoline is composed, get along well together, but the carbon car-bon would rather be combined with the oxygen than with the hydrogen, and the hydrogen would also rather be combined with the oxygen than with, the carbon. If there were a club of bachelors in the same building with a club of handsome hand-some ladies, I think it would take but a slight excuse for the bachelors to break up and join the ladies, while the ladies would probably be pleased. They would pair off, and try to get by themselves, them-selves, and if kept in the building, would probably feel cramped and under un-der a sort of pressure. In the same wny, if you bring a num-er num-er of molecules of gasoline, made up of atoms of hydrogen and carbon, in contact con-tact with a number of molecules of oxygen, oxy-gen, they will, when given the slightest reason, separate and combine with the oxygen. Heat, as from an electrical spark, will be such a reason, so that if you have a vessel containing a mixture of gasoline and oxygen molecules, and you set a spark to them, the carbon in t ho gasoline will separate from its hydrogen hy-drogen and combine with the oxvgen, each atom of the carbon combining' with I two atoms of oxygen and thus making ((' 0) carbon dioxide gap, while two ol Ihe atoms of hydrogen will combine with one of oxygon and make (H2 O) water. As the humans they will want to spread out, and if kept 'in a closed vessel they will develop a great pressure and heat. When elements combine as above, eroat heat is generated. We call the decomposition or separating, mid re-i re-i combining of the elements in the above j way combustion, or we sav thev burn. An explosion is an instantaneous combustion. com-bustion. From the above you can see wh- the mixture must be hi a definite ratio of oxygen or air ( as we get the oxvgen from the air"), and gasoline; ns, for each ji i oni of carbon there must be two atom of oxygen, and for each two atoms of j hydrogen one of oxygen. 7f thro be mi i excess of either gas or air, the excr?s i will make the amount of heat and pre?-! pre?-! sure civen out small, and mav even, by jriorbing thr hear from the spark, prevent pre-vent the combustion entirelv. i Molecules made up of certain ele-1 ele-1 nients will always want to get awn v from one another, as is the cae with the oxygen a nd nitrogen nv locales of the air. Tftus we have a gas. air technically tech-nically being gas. Others, snrh a? those : of iron, co; per, wood. etc.. will want to get together and will hold to one an-I an-I other ver firmly, giving i: a S"lid I mas. whiie it! others, surh as those i of water. w;'l have a 'slight attraction i i"or n e n u o t li o r, and so wc h 3 v e a , lie-uid. ' T 1- c rnd"U eg ' oc li ' r-ow.1 r o- li kf1 ' "'T '-v.!---- is i rjlje.i 'oh-:sien, ard that of unlike, such as glue to wood, oil to j steel, is called adhesion. The cohesion is effected by the tern-1 perature. Thus water will be in the liquid state when between 32 vnd 212 degrees fahrenheit. but will be a solid ice and snow at temperatures below this, while it will be a gas steamat . temperatures above 212 degrees. Even copper and iron will, when the temperature tempera-ture is raised high enough, melt or become be-come a liquid and in time a gas. Gasoline Gas-oline (depending upon its grade) will change from s. liquid to a gas in the neighborhood of 70 degrees. Kerosene will have to have a much higher temperature. tem-perature. The pressure above the liquid will affect af-fect the temperature at which it will change to a gas. Thus water will change to steam when the pressure is that of the atmosphere, but if the pressure pres-sure be higher the temperature will have to be raised. ' The housewife uses this law when cooking. She knows that meat, potatoes, pota-toes, etc., will be cooked quicker when the lid is left on the pot than they will when it is left off. Whv, - you ask. Because when the lid is left on the steam is high enough for it to lift the lid, and so the water will reach a higher high-er temperature and the things cook quicker. On the other hand, if the pressure be ress than atmosphere, or a vacuum, the water will turn to steam at a temperature tempera-ture less than 212 degrees. "What is true of steam is true of gasoline, gas-oline, and the fact that the gasoline will change to a gas at about 70 decrees, de-crees, which is Derhans the averaee tem perature of the air, and the fact that, duo to the suction stroke of the engine there is a vacuum in the manifold, thus making the temperature of evaporation even lower, makes it possible to use gasoline gas-oline as a fuel for the engine. The higher temperature which kerosene requires re-quires makes it impractical without the use of a heater. We want an explosion, or instan- taneous combustion in the cylinder. In order to ?et this, every molecule of the gas should be in contact or very close to a molecule- of oxygen. Thus the gasoline must get into the cylinder in the form of a gas or at worst, a fine 1 fog or mist, and be thoroughly mixed with the air. To accomplish this is the purpose, of the carbureter. Thus the definition of a carbureter is: A device for changing the liquid gasoline into a gas or mist, and to mix it with the correct amount of air to cause an in-staneous in-staneous combustion or explosion. Vacuum. What is a vacuum, and what is suction suc-tion f If you will imagine that you have drawn a square whose sides are an inch, and then consider the air being be-ing held up by this square inch, you will picture a square column of "air reaching high above tho clouds; in fact, miles high. Now air has weight, and that column will weigh about 14.7 pounds at sea level. Thus the air is under the pressure of 14.7 pounds, called the atmospheric, pressure. Because of this pressure the air will get into all space, but if you succeed in getting all of the air out of a vessel, ves-sel, it will be absolutely empty or a vacuum, and the sfia.ee will have no pressure. If we had a tank of water and inserted into this a tube and then drew the air out of the tube what would happen? Why, there would be a ''vacuum or no pressure in the tube, but the water outside is under the pressure pres-sure of the atmosphere and so some of the water will be forced up into the tube, or as we say sucked up. Having learned some of the laws upon which the action of the carbureter is based, we will take it up next. |
