306 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



Prof. Joy, of Columbia College, expressed the opinion that thallium would 

 be prepared shortly in sufiicient quantities for ordinary purposes. It is 

 found in crude sulphur, pyrites, and in mineral waters. There are two 

 oxyds of thallium, the pratoxyd and teroxyd. He had prepared eight 

 ounces of the chloryd for the purpose of spectral analysis. Thallium is 

 readily detected when in combination with other elements by its character- 

 istic, single, bright green line, coincident with B, a, delta. Its position 

 among the chemical elements is not definitely determined. A thallium- 

 alum has been made which would seem to indicate that it should be classed 

 among the metals forming alkalies. The brilliant color produced by thal- 

 lium may be of service in making combinations of colored lights and for 

 signal purposes. 



Mr. Ryan addressed the meeting on the Theory of Parallels, which has 

 long been a vexed question among geometers, and, with the aid of dia- 

 grams, attempted to deduce the properties which it is admitted Euclid 

 assumed in his thirty-second proposition under the guise of an axiom. 



Mr. Garvey briefly presented grave objections to Mr. P.'s positions, land 

 as the subject was one involving only abstractions which have long bafiled 

 the logical power of the most profound thinkers, the further discussion of 

 it was indefinitely postponed. 



The following interesting summary of scientific intelligence was presented 

 by the Chairman. 



Oxygen Gas as a Medicine. 



The use of oxygen gas as a medicine has been generally condemned by 

 the medical profession, on account of its affinities which often produce inter- 

 nal inflammation; but MM. Demarquay and Leconte advocated, before the 

 Academy of Science, Paris, its use in diphtheritis, diabetes, and other 

 exhausting maladies, when counter indications are absent. In some cases 

 the appetite returns with great intensity, the circulation is improved, lips 

 reddened and nervous affections disappear. Still no absolute cures were 

 announced by these gentlemen. The gas should be absolutely pure, and 

 administered only by those who understand all its effects. 



Influence of Ozone and other Gases on Vegetation. 



Recent experiments made by M. Ciirej^ Lee, of Philadelphia, prove that 

 the presence of ozone in the atmosphere hab the etfect of retarding the 

 growth of plants. The germination of seeds under the ordinary bell-glass 

 was not retarded by the removal of the carbonic acid from the inclosed 

 atmosphere; while in an atmosphere composed entirely of ca-rbonic acid, or 

 containing ether or nitrate of niethyle, germination was entirely prevented. 



The Mont Cenis Tunnel. 



Tliis tunnel, which is to connect the railways of France with those of 

 Italy, will be about 7| miles long. At Modane, on the French side of the 

 mountains, the tunnel is of the following dimensions: 25 feet 3| inches 

 wide at the base, 26 feet 2| inches wide in the broadest part, and 24 feet 

 7 inches in height in the middle, the arch being nearly a semi-circle. At 

 Bardonneche, on the Italian side, the height is 24 feet 10| inches, and the 



