112 Scientific Intelligence. 
phurets as a means of purification, (more especially the sulphuret of 
barium,) during the preparation of the acid. By this means also the 
nitric acid is necessarily destroyed, an acid. occurring in most of the 
sulphuric acids of commerce. 5, In 
23. Observations on an Acid Rain; by M. Ducres, (Journ. de 
Pharm., April, 1845.)—During the early part of June, 1842, a storm 
occurred in the town of Nismes, accompanied with much thunder and 
a large amount of hail. From some peculiarity in the taste of the hail, 
. the author was led to examine it more closely. Having collected a 
quantity of it, and allowed it to melt, it was found to have an acid re- 
action, which upon examination was found to be due to nitric acid, form- 
ed no doubt by the action of electric fluid on the elements of the at- 
mosphere. The occurrence of nitric acid in hail is not new, but the 
statement of this fact goes to confirm observations previously made. 
J.-L. 8 
24. Gas Pipetie; by Dr. Err- 
Line, (Ann. der Chem. und Pharm., 
Jan. 1845.)—This little instrument, 
easy of construction, will no doubt 
be found very serviceable for many 
purposes in the laboratory, as trans- 
ferring gases from vessel to_ vessel 
without disturbing their position. 
Its construction and manner of op- 
erating is very readily understood 
by referring to the annexed figure. 
Previously to using the instrument, 
the extremity e is immersed in the 
liquid over which the gas has been 
collected, and the cylinder a filled 
by sucking at d, after which the 
branch ¢ is passed beneath the re- 
ceiver and the sucking continued, — ° 
when the water will pass from a to b, and the gas from the receiver fill 
the cylinder a. It may now be transferred to another vessel by intro- 
ducing the same branch and blowing in air at d. LS. 
25. Iridescent Silver—(In a note from Prof. Joan BrocKenssy of 
Trinity College, Hartford, Conn., to B. Sitniman, Jr.)—It is well 
known to those who are conversant with optical phenomena, that 
the brilliant play of prismatic colors exhibited by mother of pearl is 
lue to the structure of the surface ; provided the shell is cut and pol- 
ed in a particular manner. This interesting fact was announced 
to the scientific world in 1829 by the discoverer, Dr. BrewsTER, who 
