Intelligence and Miscellaneous Articles. 385 



lead, and nickel-silver, as the order of their relative degrees of heat 

 conductibility (which I have determined by experiments), and com- 

 paring the results of the foregoing experiments with the ' relative 

 conductibility of the corresponding metals for heat, we find that in 

 every experiment, excepting those of numbers 4, 10 and 17, heat 

 travelled more rapidly from the better heat conductor to the worse 

 than vice versd. Also taking the following series, viz. copper, zinc, 

 brass, iron, lead, and nickel-silver as the order of their relative 

 degrees of electric conductibility, and comparing them in like man- 

 ner, we find that in every experiment except that of number 4, heat 

 travelled more rapidly from the better electrical conductor to the 

 worse than vice versd. Also in every case where wires of the same 

 metal but of different diameters composed the arrangement, as in 

 Exps. 6, 11, 15, 18 and 20, heat travelled more rapidly from the 

 larger to the smaller wire than vice versd. 



Birmingham. 



RESEARCHES ON EVAPORATION. BY PROFESSOR MABCET 

 OF GENEVA. 



The following experiments were instituted with the view of 

 throwing some light on the tendency of certain circumstances to 

 promote or diminish the evaporation of liquids. Water and alcohol 

 were the liquids chiefly used. The results obtained by the author 

 may be recapitulated as follows : — 



1 . The temperature of a liquid, allowed to evaporate freely in an 

 open vessel, is always inferior to that of the surrounding atmosphere. 

 The higher the temperature of the atmosphere, the greater is the 

 difference between its temperature and that of the liquid exposed to 

 evaporation. Between 40° and 50° Centigrade the difference was 

 found to vary from 5° to 7° ; between 20° and 25° it varied from 

 l°i to 1°£ ; at 12° it was 0°*8 only, and between 3° and zero about 

 0°*2. The explanation of this result is obvious. The evaporation 

 of a liquid diminishing with the external temperature, the cold, 

 which is the consequence of this evaporation, must diminish in the 

 same proportion ; and if it were possible to prevent evaporation, 

 altogether, the author presumes that there would be no difference 

 whatever between the temperature of a liquid and that of the sur- 

 rounding medium. 



2. The temperature of liquids, such as water and alcohol, as well 

 as the rapidity with vvhich they evaporate, varies, all other circum- 

 stances remaining the same, according to the nature of the vessel in 

 which these liquids are contained. For instance, the temperature of 

 the surrounding atmosphere being from 15° to 20°, water is on the 

 average C, 3 warmer in an open metallic vessel than in a similar one 

 of polished porcelain, and o, 2 warmer than in a similar one of glass. 

 It is the same with alcohol. Again, both water and alcohol evapo- 

 rate more rapidly from a porcelain vessel than from a metallic or 

 glass vessel of precisely the same size. For example : three similar 

 vessels, one of metal, the second of porcelain, and the third of glass, 



