42 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



ment in the motor. An engine built by 

 Korting Brothers of Hanover, fitted with 

 a vaporizer invented by Petreano, tested 

 at the Polytechnic School at Charlotten- 

 burg by Professor Slaby showed a con- 

 sumption of 550 grams of S6.2 per cent 

 alcohol by weight, which is equivalent to 

 1.21 pounds, or 1.4 pints, or a thermal 

 efficiency of 17.5 per cent. This result 

 showed an advance of nearly 50 per cent 

 in thermal efficiency over the Grobb en- 

 gine tested a year or so earlier by Pro- 

 fessor Hartmann. Following this improve- 

 ment there resulted a continual develop- 

 ment of the alcohol motor, interest in 

 which was kept up by exhibitions in 

 which prizes were offered and by scien- 

 tific societies. The most important of 

 these are given below: 



Exhibition at Halle-on-Saal, Germany, 

 .Tune 13-18, 1901. 



Exhibition (national) at Paris, France. 

 November 16-24, 1901. 



Exhibition at Berlin, Germany, Febru- 

 ary 8-lfi, 1902. 



Exhibition (international) at Paris, 

 France. May 24- June 1. 1902. 



Exhibition at Madrid, Spain, late in the 

 year 1902. 



Congress at Montpellier. October 11-21, 

 1902. 



Congress at Paris, France, March 11-17, 

 1902. 



Exhibition (international) at Vienna, 

 Austria. April 2-June 12. 1904. 



Exhibition at Rome, Italv, February 6- 

 16, 1904. 



Besides the above named, there were 

 many others of lesser importance, all con- 

 tributing to the rapid development of 

 this class of machine. 



The results of this development may 

 be summed up by saying that the thermal 

 efficiency of the motor was raised to 

 something over 30 per cent, which is 

 quite a remarkable showing in compari- 

 son with the original figure of 12.2 per 

 cent in 1894./ It must be clearly under- 

 stood, however, in interpreting these fig- 

 ures that they are the best possible at- 

 tainable at the time reported. They in- 

 dicate, so far as the fuel costs are con- 

 cerned, that with a motor specially con- 

 structed for alcohol the fuel prices per 

 gallon might be twice as much for alcohol 

 as for petroleum distillate and still give 

 power for less money, assuming that at- 



tendance, repairs, lubrication, etc., cost 

 no more in the case of the alcohol engine. 

 The Office of Experiment Stations of 

 this Department, in connection with its 

 Irrigation and Drainage Investigations, 

 has tested a number of different types of 

 gasoline engines with alcohol, and ob- 

 tained figures which show the compara- 

 tive consumption of gasoline and alcohol 

 in the same engine. The detailed results 

 of these tests will be published in a tech- 

 nical bulletin, but the general results 

 may be given here. The first tests were 

 made without any particular attempt at 

 obtaining the best adjustment of the en- 

 gine for each fuel, and showed a consump- 

 tion of alcohol two to three times as 

 great by weight per horsepower hour as 

 was necessary with gasoline or kerosene. 

 These figures indicate the necessity or de- 

 sirability of determining the proper con- 

 ditions of adjustment, because these were 

 found to have a serious influence on the 

 amount of fuel consumed. With care in 

 adjusting the engine so as to secure the 

 most economical use of the alcohol, it 

 was found that, under like conditions, a 

 small engine consumed 1.23 pounds of al- 

 cohol to 0.69 pounds of gasoline per brake 

 horsepower hour — that is to say, with the 

 best adjustment of the engine for each 

 fuel there was required 1.8 times as much 

 alcohol by weight as gasoline per brake 

 horsepower hour. It was also shown in 

 making this adjustment that it was pos- 

 sible to burn more than twice as much 

 alcohol as stated, by improper adjust- 

 ments, and still have the engine working 

 in an apparently satisfactory way. The 

 range of excess gasoline which might be 

 burned without interfering seriously with 

 the working of the engine was not so 

 great, being a little less than twice as 

 much as the minimum. These early ex- 

 periments, therefore, confirmed the early 

 results secured in Germany, to-wit, that 

 an engine built for gasoline or kerosene 

 will, when unchanged, require about twice 

 as much alcohol by weight for the same 

 work; but they also indicate something 

 that is not pointed out by the reports 

 sent us from abroad — that Is, the great 

 importance of securing the best adjust- 

 ment of the machine. 



