HALOID COMPOUNDS OF SILVER, MERCURY, LEAD, AND COPPER. 1131 
brought to zero. The water was then heated, being constantly stirred to produce 
uniformity of temperature throughout the whole mass, until the needle had been 
forced round to 180° of arc. The number of degrees of heat being read off, showed 
the heat necessary to produce a certain known expansion, and from this the coefficient 
of expansion was easily ascertained. Five results gave 10° C., 10°, 10°, 10°, 9 0, 5. The 
coefficient deduced from the mean of the determinations was for 1° O. 
•0000193083. 
Now Lavoisier gives it as *00001910; Daniell -00001951 ; Fizeau (determined by 
the same method as that which he applied to the iodide, chloride, and bromide of 
Section through the trough, longitudinally, showing the mode of 
bar, and the position of the levers. 
suspension of the 
End section of the trough, showing one of the levers, and the bar which carries it. 
