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S. L. MILLER 



that organic compounds might be synthesized by ultraviolet hght and by electric 

 discharges in the proposed reducing atmosphere. 



Experimental support for these theories came from studies of the action of 

 electric discharges on these gases [5-7]. The experimental results will be sum- 

 marized, and some of their impUcations will be discussed. 



As a basis for discussion the following model of the primitive Earth is pro- 

 posed. The atmosphere was reducing and the oceans covered an appreciable 

 fraction of the surface of the Earth. The temperature is assumed to have been 

 less than 100°. The sources of energy for the production of the initial organic 

 compounds were ultraviolet Hght, electric discharge and high temperatures 

 (under local conditions such as volcanoes). Although the level of radioactivity 

 was higher than at present, the energy available was still quite small, and there 

 is no evidence that the cosmic ray intensity was ever large enough to compare 

 with the energy from the sun. 



The energy from ultraviolet hght would probably be greater than that from 

 electric discharges. Because of the difficulties of working with ultraviolet hght 

 in the region where the reduced gases would absorb (<2000 A), electric dis- 

 charges were used in the first experiments. 



SPARK DISCHARGE — RUN i 



An approximation of the proposed model is shown in Fig. i. The apparatus 

 is made of Pyrex with tungsten electrodes. The water in the small flask is boiled 

 to promote circulation and to bring water to the region of the spark. The pro- 

 ducts of the discharge are condensed and flow through the U-tube, which 

 prevents circulation in the wrong direction. The non- volatile compounds 

 accumulate in the small flask. The spark discharge is produced by a high fre- 

 quency Tesla coil having a peak of 60,000 volts. 



Fig. I. Spark-discharge apparatus 



