The nearer the alcohol is to pure, the greater the maximum horsepower of the engine. The per cent reduction in maximum horsepower for 80 per cent alcohol as compared with that for denatured alcohol used, was less than one per cent, but the starting and regulating difficulties are appreciably increased.
With suitable compression, mixtures of gasoline and alcohol vapors (double carburetters) gave thermal efficiencies ranging between that for gasoline (maximum 22.2 per cent) and that for alcohol (maximum 34.6 per cent) but in no case were they higher than that for alcohol. The above thermal efficiencies are calculated from the brake horsepower and the low calorific value of the fuel, which for the gasoline was 19,100 British thermal units per pound, and for the denatured alcohol was 10,500 British thermal units per pound.
As has been previously published, alcohol can be used with more or less satisfaction in stationary and marine gasoline engines and these gasoline engines will use from one and one-half to twice as much alcohol as gasoline when operating under the same conditions. The possibilities, however, of altering the ordinary gasoline engines as required to obtain the best economies with alcohol are very limited; for the amount that the compression can be raised without entirely redesigning the cylinder head and valve arrangement is ordinarily not sufficient, nor are the gasoline engines usually built heavy enough to stand the maximum explosive pressures, which often reach six and seven hundred pounds per square inch. With the increase in weight for the same-sized engine designed to use alcohol instead of gasoline, comes an increase in maximum horsepower of a little over thirty-five per cent (35%), so that its weight per horsepower need not be greater than that of the gasoline engine, and probably will be less.
The work was taken up to investigate the characteristic action of fuels used in internal combustion engines with a detailed study of the action of each fuel (gasoline and alcohol) as governed by the many variable conditions of engine manipulation, design and equipment. These variables were isolated, so far as possible; their separate and combined effects were determined; worked out under practical operating conditions; and led up to the conditions required for minimum fuel consumption. The results show the saving that can be obtained over conditions for maximum consumption, and also establish a definite basis of comparison under conditions most favorable to each fuel. This latter is a point of much commercial interest, and a study of the comparative action of gasoline and alcohol may be of great service in solving some of the general internal-combustion-engine problems where other than liquid fuels are used.
A large number of fundamental tests were necessary in order to clearly define conditions and interpret results. In a way they follow the work conducted by the Department of Agriculture, supplementing to a certain extent, but not duplicating bulletin 191, which gives much data of general value.
Many of the tests of internal-combustion engines have been made, but most of them, especially in this country, were by private concerns, for a specified purpose, and the results are not generally available. Furthermore, as is generally recognized by those familiar with gas, and especially gasoline-engine operation, the conditions influencing engine performance are so numerous and varied as to make the value of offhand comparison very limited and oftentimes misleading, exact comparisons only being possible under identical conditions or with reference to the actual known differences in all conditions that influence the results.
ELECTRICAL CODE REVISIONS.
At the recent meeting of the Underwriters’ National Electric Association it was decided that Cooper Hewitt lamps must have a cut-out for each lamp or series, except when contained in a single frame and lighted by a single operation, in which case not more than five lamps shall be dependent on a single cut-out. The regulators must be enclosed in non-combustible cases, and where subject to flyings of lint or combustible material, all openings through the casings must be protected by a fine wire gauze. Moore electric light tubes must be installed so as to be free from liability to mechanical injury or of contact with inflammable material. The high-potential coils and regulating apparatus must be installed in an approved steel cabinet, which shall be ventilated in such a manner as to prevent the escape of flame or sparks in case of burn-out. The apparatus in this box must be mounted on slate, and the enclosing case positively grounded. The supply conductors must comply with the rules governing low-potential systems where such wires do not carry current having a potential of over 300 volts.