Chemistry and Physics. 247 
air which contains transparent yapor differs but little from that of dry 
air. In conclusion the author brings forward an argument based upon 
the formation of dew. If aqueous vapor were as good an absorbent of 
heat as Tyndall supposes, dew could never be formed at all, since the 
phere is loaded with moisture, the dew is very heavy. If the vapor of 
water possessed as high an absorptive power as Tyndall attributes to it, 
only a small portion of the heat radiated from the earth could reach the 
oO 
clouds, and the effect of clouds in preventing the formation of dew could 
kland i 
», Ge 
2. On some new forms of electrical apparatus —Torier and Hoxtz 
have described independently, but at about the same time, new forms of 
electrical machines which may be regarded most simply as rotating elec- 
trophori, Tépler’s machine, which is the simpler of the two, consists 
essentially of a circular plate or disc of thin vulcanized rubber, gutta 
sagan or glass, mounted upon a vertical axis and caused to rotate egies 4 
alternately. It will be seen that so far the apparatus is exaetly equiva- 
to an electrophorus, and that the action, though powerful at first, 
i ] 1 
