488 



SCIENCE. 



[N. S. Vol. XIX. No. 482. 



becomes the handmaid, or better still the 

 adviser, of the state. 



More than a quarter of a century ago it 

 became evident that stone fortifications 

 are worse than useless in the presence of 

 modern armaments; but as a people we 

 have yet to learn that the stone building 

 which is about to be dedicated is one of 

 the bulwarks of the nation. The executive 

 bra-nch of our government has learned it 

 partially; the legislative branch not at all. 

 I look forward with hope— and even con- 

 fidence—to the day when science will be in 

 in the saddle, not for science 's sake so much 

 as for America's sake. 



And it is precisely in Palmer Hall that 

 young men and young women are going to 

 learn that accuracy of speech and thought 

 which is at once the first step in morality 

 and the best preparation for action. Here, 

 if anywhere, will be acciuired productive 

 scholarship. 



Could we have with us the man whose 

 life and character is celebrated to-day 

 throughout this broad land no one would 

 be more enthusiastic than he in applauding 

 the purposes of this institvition and in ac- 

 knowledging our national indebtedness to 

 this and to similar foundations. 



Upon the teacher of science, perhaps, 

 above all others falls the duty of insisting 

 with Lotze that 'while the scientific method 

 may not be the royal road to salvation it 

 will at least keep us from straying very 

 far from the path.' 



And when on the morrow Old Glory is 

 raised above this beautiful structure let us 

 salute her as marking one of our national 

 defenses. Henry Crew. 



Northwestern Universitt. 



THE SCIENCE OF SMOKE PREVENTION. 

 Perhaps a better statement of the sub- 

 ject would be ' The Science of Perfect Com- 

 bustion, ' for perfect combiistion is attended 

 by no visible smoke. It is always best in a 



discussion of this kind to define terms be- 

 fore making statements. The Century 

 Dictionary says that smoke is 'the exhala- 

 tion, visible vapor, or material that escapes 

 or is expelled from a burning substance 

 during combustion' while the Encyclopedia 

 Britannica states that 'Usually the name 

 smoke is applied to this vaporous mixture 

 discharged from a chimney only when it 

 contains a sufficient amount of finely di- 

 vided carbon to render it dark-colored and 

 distinctly visible.' For us who live in the 

 soft-coal belt the definition may be further 

 narrowed down, for when we say smoke we 

 mean the densely-laden fumes from the 

 combustion of soft coal which deposit thick 

 layers of soot on all exposed surfaces. The 

 smoke from hard coal, coke and wood is so 

 innocuous compared with that just men- 

 tioned that it may be entirely disregarded 

 in the discussion. 



The occasional production of dense black 

 smoke is peculiar to that group of fuels 

 known as hydrocarbons, of which the more 

 common are the petroleums and bituminous 

 coal. The combustion of hydrocarbons 

 seems to be always complete at first. If 

 one watches the slow burning of a lump of 

 cannel in the open grate he will see a 

 whitish or yellowish vapor expelled from 

 the coal by the gradual heat of the fire. 

 This is the carbon and hydrogen combined 

 which is distilled by the heat and leaves 

 behind the free carbon as coke. While the 

 escape of this vapor unburned represents 

 a distinct loss of heat, the vapor is not 

 smoke as we understand it. It does not 

 deposit soot and will not stain or disfigure 

 surfaces in its path. 



As the heat increases and air is supplied 

 the vapor ignites and burns with a yellow 

 flame showing the presence of solid par- 

 ticles. If the temperature remains high 

 and the air supply continues, the combus- 

 tion is complete and the colorless carbon 

 dioxide and water vapor pass up the chim- 



