Proceedings of a conference to determine whether or not there is a public health question in the manufacture, distribution, or use of tetraethyl lead gasoline / Prepared by direction of the surgeon general.

  • United States Public Health Service
Date:
1925
Catalogue details

Licence: Public Domain Mark

Credit: Proceedings of a conference to determine whether or not there is a public health question in the manufacture, distribution, or use of tetraethyl lead gasoline / Prepared by direction of the surgeon general. Source: Wellcome Collection.

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    forms of iodine which are colorless. We found it was purely a molec- ular proposition and had nothing to do with the color, and we also demonstrated it by the use of some other colored materials that sup- plied the color but did not produce the other results. So finally we had this one material which we could introduce, which was a starting point from which we could make comparisons. It took about 3 per cent iodine to be equivalent to 40 per cent benzol, and our methods of rating gasoline have been based on this line. We were taking a certain standard gasoline and adding 40 per cent benzol to it. That permits a certain raising of compression and a certain operation of the motor. We accepted that as a stand- ard of compressions. Of course, iodine was out of the question from a commercial standpoint because of its not being obtainable. Another very interesting thing in the use of benzol, or of iodine, was that it helped to produce carbon. So your cylinder would fill up very quickly with a very flaky type of carbon. I mention the word carbon. In the ordinary garage they will say, “ Get the carbon cleaned out of your motor.” The reason for that is that the carbon is one of the best heat insulators we have. | A small cake of carbon on the inside of the motor takes up space, it raises compression, and it slows the conduction of heat from the residual gases to the cylinder wall, and the difference between a satisfactory burn and an abnormal burn is very delicate when it ‘comes to the point of temperature. A few degrees plus or minus will throw the thing from a satisfactory operation to an impossible operation. I have seen that tried out on airplane motors, and it is rather interesting. Take a motor and a fuel condition which you can make normal; get up in the air and level off, fly along definitely, and finally open your throttle to a point where you ought to get an abnormal rate of burn. You go along and you get one detonation. I use the word detonation because that expresses the idea; whether it carries along the scientific factors of detonation we do not know, because it is purely a question of degree. You might get one detona- tion, in 15 seconds another, and in a very short period of time your motor will be detonating completely, and you will have to come down. Once you get one detonation in the cylinder you immediately throw a large quantity of the heat of the explosion, by radiation of energy, into the cylinder walls and heat them. With the next com- pression it gets hotter, and you get more heat into your cooling waters; it gradually rises in temperature and you pass from a normal to an abnormal operation on an apparently slight change in the thermal condition of the motor. We then made a search of various other chemical compounds, and found aniline had a similar effect. We did a great deal of work on
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