350 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



II. The intervals in the different groups may be expressed in very simple 

 numbers, as I, 2, 3. 



III. The difference in the wave-length between the corresponding lines 

 in a group is the same throughout the whole spectrum. 



IV. The principal corresponding lines or groups of lines are equi-distant 

 in regard to the wave-lengths. 



These lines can only have one of the two following sources. They are 

 either produced by the dimensions of the solid particles, or by the intervals 

 between them, i. e. their distances. The latter is impossible, for these lines 

 remain absolutely the same under such different circumstances as cannot 

 but, to some extent, change the mutual distances of particles. Hence the 

 lines must be produced by the bulk of the particles or atoms themselves, 

 and an exact knowledge of these laws and distances must lead us to a 

 knowledge of the relative dimensions of atoms. 



Absinthe. 



Concerning this liquid — a decoction of wormwood — used more in Europe 

 than this country, M. E. Decairne recently made the following statement 

 before the Academy of Sciences at Paris: 



1. In equal doses of the same degree of strength as brandy, absinthe 

 produces more injurious effects on the animal economy. 



2. It causes iutoxication more rapidly, and its influence upon the nervous 

 system resembles more that of an acrid narcotic poison than that of intoxi- 

 cation by alcohol. 



Color of Emerald. 



Several of the Paris Academicians have expressed the opinion that the 

 color of the Emerald is due to the oxide of Chrome, and not to organic mat- 

 ter, as had been previously suggested. 



Diathermic Compound. 



Prof. Tyndall has found that a solution of iodine in the bisulphide of 

 carbon entirely intercepts the light of the most brilliant flame, yet the heat 

 of the ultra red ray of the spectrum passes freely through it. 



The Electrical Valve. 



This is the name of a new apparatus made by Mr. P. lleiss, for obtaining a 

 deflection of the magnetic needle by the secondary current of the Leyden 

 battery, which has never before been accomplished. 



Petroleum Wells. 



The discussion of the subject was opened by Dr. Rowell, who presented 

 at length the views of Prof. E. W. Evans, of Marietta College, Oliio, regard- 

 ing the various phenomena observed at petroleum wells in Western Ohio 

 and Northern Virginia, published in Sllliman's Journal for September, of 

 which the following is an abridgement: 



"The principal supplies of petroleum are not diffused between planes of 

 stratification, but are collected in cavities where it is loss liable to be car- 

 ried away by running water. It is common to find large quantities iu 



