198 A. WM Mayer—Remarks on Dr. R. Radau’s paper. 
Although multiplied trials have failed in separating the intru- 
sive mineral, in a pure state, we have the evidence of its extra- 
ordinary power of action on light, in its partially decomposed 
condition, and in some trials we can see it naturally engaged in 
the mass, and coloring it, while its appearance at the surface 
under chemical action removes all doubt of its being the cause 
of color. It was deemed important that the feature of suffici- 
ency of this cause of color should be supported by analogy, 
and I have sought in several directions for facts of this kind. 
1 submit one of these. : 
The mineral carnallite presents in some specimens a full rich 
red color. By fracturing and selection samples were made 
ments of Prof. G. Rose were published in this country. 
In numerous trials no feature favoring the presence of other 
causes of color has been observed, and this ore must take 1ts 
place with other minerals whose colors are due to foreign miD- 
erals crystallizing with or intruding into them. 
The detection of molybdenum in this ore is easily effected by 
evaporating a neutral chlorhydric solution to a syrupy COD 
sistence on a hasp formed of zine and platinum. The platinum 
becomes black and covered with a coating, which dissolves 
potassium bisulphate, or phosphoric hydrate as altered by heat, 
in a state fitted for testing. 
Brookline, Mass., 10th July, 1872. 
Art. XX VIL—Remarks on Dr. R. Radau’s paper in Dr. Carl's 
“ Repertorium” (vol. viii., no. 1), entitled “ Remarks on_ the vv 
fluence of a motion of Translation of a Sounding Body 
the Pitch of the Sound ;” by AurreD M. Mayer, Ph.D. 
In the last number of Carl's Repertorium, Dr. R. Radan, of 
Paris, writes an article, bearing the above heading, of which 
the following is the opening paragraph : see 
“The simplest means of showing the influence of a motion © 
the source of sound on the apparent pitch, an effect first sué 
pected by Doppler, is, perhaps, the application of two tuning 
