390 EXPERIMENT STATION RECORD, [Vol. 38 



will be one of the most useful tests that the refiner employs, but it is of but 

 little value to the analyst who does not possess sufficient additional informa- 

 tion to make proper interpretation of gravity results. . . . 



"Volatility is the basic property that determines the grade and usefulness 

 of a gasoline. . . . General consideration of the numerous factors Involved 

 has led to the following conclusions regarding the desirable characteristics of 

 the volatility of motor gasoline: Gasoline should contain a moderate but not 

 excessive proportion of low-boiling constituents, enough to permit easy starting 

 of a cold engine but not enough to make evaporation losses excessive. Gaso- 

 line should have a total volatility range wide enough to include constituents 

 that have a high, but not too high, boiling point. For economic reasons affect- 

 ing both the individual user and the country as a whole, this volatility range 

 should be such that the gasoline contains the largest possible percentage of 

 the original crude oil. It should not, however, be wide enough to exceed the 

 Mmits of the vaporizing power of the automobile engine." 



In the proposed specifications for motor gasoline it is required that the 

 color be water white and that acidity be totally absent. 



" The gasoline shall, when distilled by the method described, meet the fol- 

 lowing requirements: (1) The temperature read on the thermometer when 20 

 per cent has distilled shall not be below 70° C. (158° F.) nor above whatever 

 limit is fixed after due consideration of conditions of use. (2) The tempera- 

 ture read when 90 per cent has distilled shall not be above another limit 

 similarly chosen. (3) The temperature read when 50 per cent has distilled 

 shall not be higher than a mark half way between the 20 per cent and the 

 90 per cent limit. (4) The dry point shall not exceed the actual 90 per cent 

 reading by more than 55°. 



" Tolerance. — If either the 20 per cent or the 90 per cent temperature mark 

 is above the required limit by an amount not exceeding 10°, the gasoline may 

 be considered acceptable if the sum of the two temperatures read for the 20 

 and the 90 per cent marks do not exceed the sum of the adopted limits." 



Distillation methods and apparatus are described and specifications given 

 therefor. 



Tractor facts for Oklahoma farm.ers (Oklahoma City, Okla.: Oklahoma 

 Farmer, 1917, pp. 37, figs. 49). — This is a brief summary of information, favor- 

 ing the use of the tractor on Oklahoma farms. 



Harvesting and plowing simultaneously with, a tractor, M. Ringelmann 

 (Bui. Sac. Encour. Indus. Nat. [Paris], 116 {1911), I, No. 3, pp. 595-599, figs. 

 2). — The details of this procedure as practiced under French conditions are 

 described. Experiments in 1916 showed that a hectare (2.47 acres) of grain 

 could be harvested and bound and the ground plowed in 2 hours and 36 min- 

 utes at an expense for the tractor of about -26.54 francs ($5.12). 



Handling silage, L. W. Chase {Univ. Nebr., Col. Agr. Ext. Bui. 45 (1917), 

 pp. 16, figs. 14). — Devices for harvesting, hauling, unloading, cutting, placing, 

 and removing silage are described and illustrated, with particular reference 

 to pit silos under Nebraska conditions. 



Utilizing exhaust steam for heating water and for pasteurizing (U. S. 

 Dept. Agr., Bur. Anim. Indus. Milk-Plant Letter 43 (1917), pp. 2). — This is a 

 mimeographed letter in which attention is called to the value of exhaust steam 

 from milk plants for pasteurizing and heating boiler feed water. Data are 

 also given showing how the coal bills of different plants vary according to 

 the plant efficiency. 



" The heating of feed water from 50 to 200° F. by the use of exhaust steam 

 will directly reduce the fuel consumption by about 13 per cent. The actual 

 saving in fuel, however, is greater than that, owing to the more even firing. 



