130 Scientific Intelligence. 



very broad, while others are quite fine and require a prism of high dis- 

 persive power to effect their resolution. 



Annexed is a drawing obtained by micrometrical r 

 ing their position as compared with some of the fixe 



n rr fi 



D, or the sodium line is just cut off by one of these broad band?, and 

 from this results the singular circumstance that the sodium flame be- 

 comes invisible when merely viewed through a foot of the solution, 

 though white objects examined in the same maimer appear but slightly 

 altered in tint. This, I think, is the only case we know of where the 

 orange ray is cut off by a nearly colorless medium. 



Very sincerely, O. N. Rood. 



Troy, May 21st, 1862. 



' powdered Ice in water boiling in Glass Vessels ; by Pro^^ 



Chadbourne, of Bowdoin College. — The common experiment c 

 ig iron filings into water slowly boiling in smooti 



dered ice or granular snow for the iron filings. Snow that has thawed 

 partially and then frozen so as to become hard and granular is the best, 

 ' t powdered ice will answer if kept so cold by freezing r ' '" '^^ 



filled with water slowly boiling, 

 takes place, a portion of the water being thrc 



perfectly dry. If a spoonful of this ice or snow be thrown into a smooth 



^ cles of ice" thus act like particles ot'^iron or sand, before they 1 



3. Galvanic Experiment.— li is well known that the directions for repeat- 

 ing this experiment are, that one metal shall touch the nerve of tin- 'i' ;■ 

 the other meta! the muscle. If instead of this arrangement the i- 

 dissected out from the thigh of the frog and the current passe^l *' 

 the nerve alone the movement of the leg will be equally great. 

 pa.ssing a current directly through one section of the nerve will ; 

 contraction, one end of the nerve may be separated and wouli- 

 thread around one wire, then by touching any portion of the norve t:iy> 



separated so as to pass a current through i' ' ' "" "^ '"■"" 



By touching c • ■ - 



