A NEW BIETHOD OF ILLUMINATING A TOWN. 753 



with great doubt as to the result that I decided to submit^it to the same 

 tests whicli had determined the liquefaction of all the other gases. 



"In my first attempt I noticed nothing particular, but, as often happens 

 in experimental science, skill in observing phenomena results in causing 

 signs to be recognized under conditions where they had at first escaped 

 notice. 



"This is what occurred with hydrogen : On repeating my experiments 

 to-day, in the presence of MM. Berthelot, H. Sainte-Claire Deville and 

 Mascart, who have allowed me to quote their testimony, T have succeeded 

 in observing indications of the liquefaction of hj^drogen under conditions 

 of proof which have left no doubt on the minds of the scientific men who 

 witnessed the experiment. It has been repeated a great number of times. 

 Operating with pure hydrogen compressed to about 280 atmospheres, and 

 then allowed suddenly to expand, we saw form an extremely attenuated 

 and subtle mist suspended in the gas and disappearing suddenly. The 

 production of this mist, in spite of its extreme subtlety, seemed incontest- 

 able to all the scientific men who witnessed the experiment to-day, and who 

 took care to have it repeated several times, so as to leave no doubt as to its 

 reality. 



"J.2r. — Having liquefied nitrogen and oxygen, the liquefaction of air is 

 thereby demonstrated. It appears, however of interest to make this the 

 subject of an actual experiment, and, as might be expected, it succeeded 

 perfectly. I need not say that the air was previously dried and freed from 

 carbonic acid. The accuracy of the views expressed by the founder of 

 modern chemistry, Lavoisier, is thus confirmed as to the possibility of 

 causing air to assume the liquid state, and of producing matter gifted with 

 new and unknown properties — views recalled so appropriately at the last 

 meeting of our illustrious perpetual secretary." — London Chemical News. 



A NEW METHOD OF ILLUMINATING A TOWN 

 BY PROF. E. L. BERTHOUD, COLORADO SCHOOL OP MINES. 



In 187-4-75 I was examining the question of the lighting of a small 

 town in Eastern Colorado, and the cheapest and easiest method attainable. 

 I went over the usual routine of gas, petroleum, and all of the so-called 

 cheap gases and gas processes. 



Happening to know that the Foreland Light-house in England was illu- 

 minated by an electric light, I obtained some data from England in regard 

 to this method, which, successful, has been in use many j^ears, but being 

 originally and then kept up by a large battery, was expensive and rather 

 •complicated. Since 1874 however, Mr. Grramme, in France, has invented 

 and patented an easy and cheap method of obtaining a constant flow of 

 electricity by an electrical frictional machine of great power and constancy 

 smuch superior in cheapness and in constancy to the combination of Daniells 



