Chemistry and Physics. 273 
into two parts he first division, which is of a more elementary 
nature, treats of the principles of the wave theory for the simple case 
of isotropic media. ‘[he explanation of the attributes of color, intensity 
Catoptrics and Dioptrics are theoretically deduced. ‘This portion of 
the work is in itself a very full treatise on descriptive Photics, though 
ina few particulars, as for example, upon the subject of circular polar- 
ization, more details would have been desirable. The chapter on inter- 
ference is particularly worthy of notice, the subject ee treated in 
: s 
description of Fessei’s wave machine, for the representation of plane 
circular and elliptically polarized waves, as well as for the illustration 
nomena of the motion of light in crystalline media. The treatise con- 
Work. Upon the whole, then, we regard Dr. Beer’s treatise as one o 
the most truly important and valuable contributions to scientific literature 
Which have a peared in recent times, and it is to be hoped that it may 
on appear in an English dress, and thus become more generally ac- 
Cessible and useful. 
4. Die Lehre von der Reibungselektricitét von P. T. Riess.—Prof, 
Hess is one of the few physicists who has devoted his energies exclu- 
Sively to the subject of frictional electricity—a subject which, though at 
one time very popular, has of late years been but little studied. The 
treatise before us i 
t e excitement of electricity, and the sixth of atmospheric 
electricity, The author abstains entirely from theoretical considera- 
» and devotes his work exclusively to phenomena an laws, 
A great mass of isolated experiments with which works on electri- 
ity usually abound serves only to confuse the subject, and Prof. Ri 
. it 85 ade tas ze 
