Chemistry and Physics. 67 
it be hydrogen peroxide alone, or mixed with ozone, or perhaps 
also with other constituents hitherto unknown. ‘The objection to 
ozone does not act on these papers, they must be moistened; and 
then the amount of moisture varies the result quite as much as 
the amount of ozone. Indeed, attention has been called to the 
B'S 
the thallium-paper, the oxidation to brown oxide by either ozone 
or hydrogen peroxide, not requiring the presence of moisture, and 
the color therefore being independent of the hygromeiric state o 
the air. Moreover, when well cared for the papers undergo no 
~ e . 
tains 10 grams TI(OH). For use the strips are hung in the free 
ometer, the relative humidity, cloudiness, rain, and velocity of 
wind.— Ber. Berl. Chem. Ges., xiii, 1508, Sept., 1880. G. F. B. 
3. On the nature of the Petroleum from the Caucasus,—Brt- 
STEIN and Kursatow have examined the more volatile portions 
of the petroleum obtained at Baku in the Caucasus, in order to 
compare this material with American petroleum. It had been 
observed that the Caucasus fractions had a greater specific grav- 
ity than American fractions of the same boiling point; and this 
fact led to a distrust of the illuminating oils prepared from the 
